ACETAL
Hemiacetals, in the presence of an acid catalyst, react with alcohols
and form acetals. These 1,1-diethers form when an aldehyde is heated together with
sufficient alcohol and a trace of acid catalyst. Unlike hemiacetals, acetals may be isolated
and purified. When warmed with water in the presence of acid, however, they
change back to their original aldehydes and alcohols.

ACETOACETATE
Aceoacetate can spontaneously give up carbon dioxide to form acetone.

ACETOACETYL COENZYME A
Biosynthesis from amino acids.

ACETONE
Acetone is an important organic solvent because it dissolves both water
and nonpolar solvents. It is very volatile and therefore very flammable.

ACETYLENE
Compounds in which carbon-to-carbon triple bonds occur are alkynes, nicknamed
acetylenes. The smallest member of this family is acetylene.

ACIDOSIS
A drop in the pH of blood to lower, more acidic values is a condition called
acidosis.

ACID
An acid is any substance that will produce in water a higher concentration of hydronium
ions than hydroxide ions.

ACTIVATION Energy Of
The energy needed to surmount the barrier is called energy of activation.

ADENOSINE TRIPHOSPHATE
The most widely occurring member of this family, is involved directly or
indirectly in most of the energy-consuming reactions of metabolism.

ALCOHOLS
Alcohols react with aldehydes to form unstable addition compounds called
hemiacetals. Alcohols also react further in the presence of a trace of acid catalyst to
form 1,1-diethers called acetals. Primary alcohols can be made by the catalytic
hydrogenation of aldehydes, and secondary alcohols by a similar reduction of ketones.

ALDEHYDES
Aldehydes, like mercaptans, are easily oxidized. Their oxidation produces
carboxylic acids. Two mild reagents for oxidizing aldehydes are the Tollens'
and Beneditct's reagents. Aldehydes are also reducible, forming 1 degree alcohols
when hydrogenated. In water aldehydes form an equilibrium with corresponding
1,1-diols, and in alcohols, aldehydes form a similar equilibrium with hemiacetals.

ALDEHYDE HYDRATES
If the aldehyde is in the form of its hydrate, then the oxidation may be viewed
as the dehydrogenation of one of its alcohol groups.

ALDOHEXOSE
A hexose that possesses an aldehyde group is called an aldohexose.

ALDOSE
If an aldehyd, the monosaccharide is an aldose.

ALDOSTERONE
Aldosterone helps stabilize the sodium ion level in blood.

ALKALOIDAL REAGENTS
May affect both salt bridges and hydrogen bonds. These reagents
precipitate proteins.

ALKALOIDS
Alkaloids are basic, nitrogen-containing, usually heterocyclic compounds
that are produced by plants. They have a marked physiological activity.

ALKALOSIS
A rise to more alkaline values.

ALKANES
Molecules in the alkane family are saturated, that is, they possess only single
covalent bonds.

ALKENES
If the molecules of a hydrocarbon contain carbon-carbon double bonds, the
hydrocarbon's chemical properties differ so much from those of alkanes that
we must have a new family. The systematic name for this family is alkenes.

ALKYL GROUPS
If a side chain or branch consists only of carbons and hydrogens linked
to each other by just single bonds, it is called an alkyl group.

ALKYNES
Compounds in which carbon-to-carbon triple bonds occur.

ALLOSTERIC EFFECT
The phenomenon of affecting a change in an enzyme when a modulator
binds at some site other than the catalytic site.

ALPHA RAYS
Alpha rays consist of particles moving with a velocity that is almost one-
tenth the velocity of light. Each particle is a tiny cluster of two protons and two
neutrons and is, therefore, identical with the nucleus of a helium atom.

AMIDES
Amides form by heating an acid together with ammonia or a suitable amine.
They are hydrolyzed by the action of hot water and either alkali or acid.

AMINE OXIDASES
Playing a small role in the oxidative deamination of a-amino acids, particularly lysine,
is an amino acid oxidase having FMN as the hydrogen acceptor.

AMINES
Alkyl derivatives of ammonia are called amines.

AMINO ACIDS
Twenty a-amino acids are the monomers for proteins.

AMINOPEPTIDASE
An enzyme from intestinal juice, is present to remove residues from
the N-terminus.

AMMONIA
Can neutralize strong acids.

AMMONIUM CYANATE
Is a salt and was at the time of Wohler's experiment accepted by
most scientists as inorganic or mineral.

AMMONIUM ION
Can neutralize strong bases.

ANILINE
Building block for aniline dyes; synthesis of many
pharmaceuticals.

ANTIFREEZE
These two glycols serve as the base for all permanent-type antifreezes.
Their great solubility in water and their very high boiling points make
them ideal for this purpose.

ANTIGEN
The substance that provokes the manufacture of an antibody.

ANTIGEN-ANTIBODY COMPLEX
The reaction of an antibody with its antigen produces the antigen-antibody
complex.

APOENZYME
Where a cofactor is needed the wholly protein portion of the enzyme is called
apoenzyme.

ARRHENIUS THEORY
Acids are compounds that liberate hydrogen ions in water, bases are substances
producing hydroxide ions in water, and salts are ionic compounds involving
any other ions. Strong acids or bases are those that break up into ions to the extent of
a high percent, up to 90 or 100%. The five most common strong acids are hydrochloric,
hydrobromic, hydriodic, sulfuric, and nitric acid. All are monoprotic except sulfuric,
which is diprotic.

ATOM
Is the smallest representative sample of an element.

ATOMIC MASS
The mass of the nucleus in units of amu is for all practical
purposes the mass of the atom or the atomic mass and is the sum of the protons and neutrons.

ATOMIC ORBITAL
Is a compartment of a sub-level. It is a particular part of the space
where an electron can have a high probability of being, provided
it has the appropriate energy. Associated with each orbital is a
particular amount of energy that an electron will have if present.

AVOGADRO'S PRINCIPLE
When measured at identical temperatures and pressures, equal volumes
of different gases must contain equal numbers of moles.

BACKGROUND RADIATION
From cosmic rays and from radioactive isotopes in rocks and
soil we receive an inescapable exposure to radiations to the extent
of an average of 100 to 140 mrem per person per year.

BENZENE RING
This was the flat, hexagonal ring of six carbon atoms that occurs
in the hydrocarbon benzene.

BENZOIC ACID
Starting material for many organic chemicals; used in some ointments
designed to soften the epidermis.

BETA RAYS
Beta Rays are actually electrons produced within the nucleus and then
thrown out of it. Being more than seven thousand times smaller than alpha
particles, they more easily penetrate matter.

BINDING SITES
The binding sites are a pattern of electrical charges and hydrogen-bond
donating (or accepting groups) arrayed to attract groups with complementary
patterns on substrate molecules.

BIOCHEMICAL ENERGETICS
Biochemical energetics in its simplest analysis thus comes down to the
manufacture of ATP by the use of chemical energy in such substances as
glucose, fatty acids, amino acids and oxygen.

BIOCHEMISTRY
Biochemistry is the systematic study of the chemicals of living systems, their
organization, and the principles of their interaction as they participate in the
processes of life.

BIOLOGICAL MEMBRANES
Biological membranes are structures that hold individual cells together or that
hold together organelles, small bodies inside cells such as mitochondria.

BOHR EFFECT
The combined action of hydrogen ion and carbon dioxide to make it easier
for oxyhemoglobin to give up oxygen is called the Borh effect.

BOND-Chemical
Certain situations provide atoms with opportunities to shift and reorganize
electrons between the nuclei relative to each other and to create forces of
attraction between the atoms called chemical bonds.

BOND-Covalent
Force of attraction that arises from sharing a pair of electrons.

BOND-Double
In some molecules two pairs of electrons are shared, and the resulting
very high electron density creates a very strong bond called a double
bond.

BOND-Hydrogen
A hydrogen bond is a force of attraction that extends from a hydrogen of
one water molecule ( a site of partial positive charge) to the oxygen of another
molecule (a site of partial negative charge).

BOND-Ionic
This net force of attraction between oppositely charged ions that
holds the crystal together.

BOND-Polar Bond
A covalent bond with a partial positive charge at one end and a
partial negative charge at the other.

BONDS -Triple Bond
In other molecules three pairs of electrons must be shared to create the
net effects of outer octets - the resulting bonds are triple bonds.

BOYLE'S LAW
Robert Boyle, an English scientist, discovered a relationship between
gas pressure and volume now called Boyle's law: provided the
temperature of a fixed sample of gas is held constant, the volume changes
inversely with its pressure.

BRONSTED THEORY
A base is a species that has a tendency to take and bind a proton.

BRONSTED ACID
A species that has a tendency to split off a proton.

BROWNIAN MOVEMENT
It is caused by the buffeting of colloidal particles by random motions of the
molecules of water or other dispersing media.

BUFFERS
Solutions containing an ion that can tie up added hydrogen ions and another
ion that can tie up added hydroxide ions are buffered against changes in pH.

CALCIUM CHLORIDE
Is commonly used as a dehydrating agent or desiccant, a substance that will
remove water or water vapor from something.

CARBON-Primary
When a carbon is attached directly to but one other carbon it is classified as
a primary carbon.

CARBON-Secondary
This carbon is directly attached to two other carbons.

CARBON-Tertiary
This carbon has direct bonds to three other carbons.

CARBON-Tetrahedral
This carbon has four single bonds.

CARBON CHAIN
A succession of carbon atoms covalently joined while also holding, each one,
enough hydrogen atoms to fill our four bonds from each carbon.

CARBON CHAIN-Branched
One with a carbon-containing group stuck somewhere on a chain other than
on an end.

CARBON DIOXIDE
Is one of the end products of metabolism and is made by the combustion
of any fuel-gas, coal or oil. Carbon dioxide produces an acidic reaction
in water.

CARBONIC ACID
Both a weak acid and an unstable acid, is involved in the management of
waste carbon dioxide in living things.

CARBON MONOXIDE
If the metabolism combustion is carried out incompletely carbon monoxide
is produced. It is a dangerous poison.

CARBONYL GROUP
The carbon-oxygen double bond or carbonyl group, occurs in a wide variety
of nature's most important substances-in all foods, all enzymes, most hormones,
all genes, and many vitamins.

CARBOXYL GROUP
The carboxylic acid group or carboxyl group is in all amino acids and proteins,
all fatty acids used to make fats and oils, and in many of the metabolic intermediates
of carbohydrates.

CARBOXYLATE IONS
The carboxylate ion group is one of the most effective of all organic groups
at bringing large molecules into solution in water. The fact that the solubilities
of large molecules bearing this group can be drastically altered simply by
changing the pH of the solution is a most significant fact in the molecular basis of life.

CARBOXYLIC ACIDS
The carboxylic acid group or carboxyl group is in all amino acids and proteins, all
fatty acids used to make fats and oils, and in many of the metabolic intermediates
of carbohydrates.

CARBOXYLIC ACID SALTS
Salts of carboxylic acids are ionic compounds, and the potassium or sodium salts are
very soluble in water.

CARBOXYPEPTIDAS
Carboxypeptidase helps to break off amino acid residues at the C-terminus of a
polypeptide.

CARCINOGENIC COMPOUND
Compounds containing several benzene rings are often carcinogenic; that is, they
possess cancer-producing activity.

CATABOLISM
To provide chemical energy and be catabolized. The principal end products of
complete catabolism of amino acids are carbon dioxide, water and urea.

CATALYSIS
The phenomenon of this kind of acceleration of a reaction rate is called
catalysis.

CATALYSTS
Compounds that in small concentrations will accelerate reactions without
becoming permanently changed are called catalysts.

CELL
The cell is the structural unit of life and chemicals associated with living things
are generally organized in these units.

CELLULOSE
Is a high-formula-weight polymer of glucose.

CELSIUS TEMPERATURE
In the Celsius Scale the freezing point is called 0 C and the boiling point is
100 C.

CENTIMETER
One of the most commonly used variations of the meter.

CENTRIOLE
The centriole is involved in cell division.

CHARLES' LAW
Jacques Charles, a French scientist, found the particular way in which a gas expands
in volume when its temperature is raised, provided that care is taken to retain the same
quantity of gas and keep its pressure the same throughout the experiment.

CHEMICAL PROPERTY
A chemical property is any one of the chemical reactions the substance can
undergo.

CHEMICAL REACTION
A chemical reaction is an event in which one (or more) substances are changed into
new substances.

CHEMOTHERAPY
Chemotherapy is the use of chemicals-drugs-that destroy infectious organism without
seriously harming human protoplasm.

CHLORIDE SHIFT
To replace its negative charge in the red cell, a chloride ion migrates from the serum
to the red cell, and this switch is called the chloride shift.

CHLOROFORM
Powerful, rapid-acting anesthetic, nonflammable.

CHOLESTEROL
Cholesterol is an unsaturated steroid alcohol that makes up part of the
membranes of certain cells and is the body's raw material for making the
bile salts and the steroid hormones, including the sex hormones.

CHOLIC ACID
Cholic acid is found in bile in the form of its sodium salt.

CHROMATIN
The twisted, intertwined filaments inside a cell nucleus are made of
a substance called chromatin.

CHROMOSOMES
When cell division, called mitosis, begins, each chromatin strand may be
seen to thicken. As they do, rodlike bodies become quite visible under the
microscope if a staining agent is used. These discrete bodies are the
chromosomes.

CHYME
Churning and digesting activities in the stomach produce a liquid
mixture called chyme.

CLINISTIX
A convenient qualitative test based on enzymes is commercially
available as Clinistix.

CLINITEST
Clinitest tablets are a convenient substitute for Benedict's solution.
A few drops of urine are mixed with a tablet. Heat is generated as the
tablet dissolves, and the result of the test is compared with a color
chart provided with the tablets.

COBALT-60
Cobalt-60 is a powerful beta and gamma emitter with a half-life of 5.3
years. Gram for gram cobalt-60 has a source intensity more than 200
times that of pure radium. To shield unwanted gamma radiation, the
sample is placed in a lead container 26 cm thick with an opening pointed
toward the cancerous site. All beta radiations are shielded by a thin piece
of aluminum.

CODON
Each triplet of bases on a messenger RNA strand (where U does substitute for
T) is one code "word", called a codon, that corresponds to a particular amino
acid.

COEFFICIENT CHEMICAL
The numbers appearing in the front of the formulas are called coefficients.
Coefficients tell us the proportions in which the chemicals react and are
changed to products.

COENZYME
The cofactor may be an organic species called a coenzyme.

COFACTOR
The nonprotein group in an enzyme.

COLLAGENS
In bone, teeth, tendons, skin and soft connective tissue.

COLLOIDAL DISPERSION
When particles of this size are uniformly scattered in water, the
product is not a solution but a colloidal dispersion, a mixture that is
non-filterable but is transparent only in the more dilute dispersions.

BROWNIAN MOVEMENT
It is caused by the buffeting of colloidal particles by random motions
of the molecules of water or other dispersing media.

COLLOIDAL STATE
Matter consisting of particles having average diameters of 1 to 100 nm
is said to be in the colloidal state.

COMBUSTION
Oxygen is the most common chemical that will attack alkanes, and
combustion is the most useful chemical reaction of alkanes. The most
important product is heat.

COMPOUNDS
When a compound is broken into its elements, they are always found to
have occurred together in the compound in a definite proportion by weight.

CONCENTRATON
Concentrations are described in a variety of ways, and the method selected
depends on the use to which the solution will be put. Every expression of
concentration, however, is a ratio of solute to solution (or to pure solvent)
expressed as the result of dividing the former by the latter in whatever
physical units we choose.

MOLAR CONCENTRATION
The molar concentration of a solution, symbolized by M, is defined as the
number of moles of solute per liter of solution.

CONDENSATION
When a vapor changes to its liquid state, a change called condensation,
the energy the vapor took to become vapor now returns to the surroundings.

CONDUCTION
Heat conduction occurs whenever a warmer object is in contact with
one that is colder.

COORDINATE COVALENT BONDS
Because of this difference in mode of formation, chemists call such
covalent bonds coordinate covalent bonds, and they say that the proton
"coordinates with" the water molecule. Coordinate covalent bonds vary
widely in strength.

COSMIC RAYS
Cosmic rays are streams of particles that pour into our atmosphere
from the sun and outer space. They come in showers whose intensities
are highest during periods of solar flares.

COTTON
Cotton fiber is almost 98% cellulose, wherein each molecule has
from 2,000 to 9,000 B-glucose units.

COVALENCE
The covalent-combining ability of an element is called its covalence, and it
equals the number of electrons its atoms must at least partially obtain by
sharing to have an outer oclet.

COVALENT BOND
This force of attraction that arises from sharing a pair of electrons.

CRACKING
The natural gasoline fraction of crude petroleum falls far short of being
enough for our needs. Organic chemists and engineers have solved this problem
by discovering ways to break or "crack" larger molecules found in the
kerosene range or higher into molecules small enough to be usable as gasoline.
Many unsaturated hydrocarbons are obtained by cracking operations.

CRICK-WATSON THEORY
Proposed a structure for DNA that made it possible for the first time to develop
a theory about the molecular basis for genetic information or heredity.

CUP
16 tablespoonfuls - 250 ml

CYCLOALKANES
Cyclic compounds that contain only carbon and hydrogen and that involve only
single bonds are called cycloalkanes.

CYCLOPROPANE
Cyclopropane is a sweet-smelling, colorless gas that is used in some types
of major and minor surgery as an anesthetic.

DACRON
Dacron, a polyester, is another important condensation polymer.

DALTON'S ATOMIC THEORY
John Dalton explained the laws of chemical combination by
using an old Greek idea of an atom and giving it the specific
properties that it must have if the laws are to make sense. Basic
to this theory was the notion that all atoms of one element are
identical in mass; atoms of different elements have different
masses. He also insisted that atoms are indestructible.

DALTON'S LAW OF PARTIAL PRESSURES
The total pressure exerted by a mixture of gases is the sum of the
individual partial pressures.

DECAY, RADIOACTIVE
When an atomic nucleus loses (or gains) any protons as a result of
radioactive decay, its atomic number changes. It becomes the nucleus
of an entirely different element.

DEHYDRATION-ALCOHOL
The elements of water can be removed from most alcohols by
a reaction called dehydration.

DELANEY CLAUSE
A statement in federal legislation regulating food additives, that
prohibits the use of any substance as a food additive that has been
found to cause cancer in experiments with laboratory animals.

DELIQUESCENT
Calcium chloride has the ability to take even more water than
that required for a hydrate. It can draw so much water from humid air
that a liquid solution forms. Any substance that can do this is called
deliquescent.

DENATURATION
Is a disorganization of the molecular configuration of a protein.

DESICCANT
Calcium chloride is commonly used as a dehydrating agent or desiccant,
a substance that will remove water or water vapor from something.

DETERGENTS
Detergents are surface active agents, substances that lower the surface
tension of water.

DEXTRINS
Amylopectin, under controlled conditions, yields partial breakdown
products that are collectively called dextrins.

DIASTIX
Another commercial test paper.

DIFFUSION
A gas not confined in a closed container eventually drifts and
intermingles with its surroundings. This change, called diffusion,
continues until the gas becomes more or less uniformly distributed
in its surroundings.

DIPEPTIDE
The union of two amino acids by a peptide bond.

DISACCHARIDES
Carbohydrates that can be hydrolyzed to two monosaccharide units
are called disaccharides.

DISSOCIATION
The separation and diffusion of preexisting ions.

DIVINYL ETHER (Vinethene)
This ether is another anesthetic, being more rapid in its action
than ethyl ether. It forms an explosive mixture with air.

DNA
Deoxyribonucleic acids

DOSE EQUIVALENT
To put different kinds of radiations on the same scale, the unit
of the rem has been defined, and it is the unit for a quantity called
the dose equivalent.

DRAM
60 grains

ELASTIN
In many places where collagen also occurs, but particularly in ligaments,
the walls of blood vessels and necks of grazing animals. Elastin is not
changed to gelatin by water.

ELECTRICAL BALANCE
The net charge on all reactants equals the net charge on all products.

ELECTROLYTES
This simple distinction serves to classify substances as conductors.

ELECTRON
Is electrically charged, which means it can exert pushes and pulls -
forces of repulsion and attraction - without physically touching.

ELECTRON CLOUDS
Regions with negative charge density.

ELECTRONEGATIVITY
The ability of an atom to draw electron density toward itself when
covalently bound to another atom.

ELECTRONIC CONFIGURATION
The distribution of electrons among available levels is called the electronic
configuration of the atom.

ELECTRON TRANSFER
Electron transfer is one kind of chemical reaction.

ELECTRON-VOLT
When one electron is made to move from rest under the influence
of 1 volt, then the energy of the electron is said to increase by
quantity called one electron-volt.

ELECTROVALENCE
Another name sometimes used for oxidation number is
electrovalence (from the Latin valere, to have power, to be
strong), because it connotes combining ability, but the two terms
are not equivalent.

ELEMENTS
Substances that cannot be broken down into anything simpler and
yet stable.

EMULSION
A colloidal dispersion of two liquids in each other.

EMULSIFYING AGENTS
Agents that stabilize emulsions.

ENDERGONIC CHANGE
Some chemical changes will not occur unless the materials constantly
receive outside energy, usually heat - the general term.

ENDOTHERMIC CHANGE
Some chemical changes will not occur unless the materials constantly
receive outside energy, usually heat. This term is used when only heat
is involved.

END POINT
When this color change takes place, we say that the end point has
been reached, because this is the end of the titration.

EQUIVALENCE POINT
The precise point at which all available hydrogen ions (or hydroxide ions)
have been neutralized is called the equivalence point of the titration.

ENERGY
Energy is a capacity for causing change.

ENERGY DENSITY
Lipid has a much higher energy density than carbohydrate; it stores more
calories per gram of tissue.

ENERGY LEVELS
Electrons are restricted to certain particular regions called energy states or
energy levels.

ENERGY OF ACTIVATION
Carbon and oxygen, relative to carbon dioxide, are on an energy hill but behind
an energy barrier. The energy needed to surmount the barrier is called the energy
of activation.

ENZYMES
Some enzymes are made wholly of one or more polypeptide strands and others have
a cofactor. Names of enzymes nearly always end in -ase and also indicate either the
substrate or the type of reaction. Enzymes work best under an optimum pH and
temperature. The reaction rats they make possible are extremely high. Enzymes are very
specific in both the type of reaction and the specific substrate they affect. Conditions
that denature proteins denature enzymes. The analysis of enzyme concentrations in body
fluids is useful in diagnosing several diseases.

ENZYME-SUBSTRATE COMPLEX
A molecule of enzyme and a molecule of substrate combine by noncovalent forces
to form this.

EQUATIONS (Chemical) - Balancing
Balanced equations are essential in experimental and analytical work because their
coefficients give the proportions by moles of the reactants and products. To balance
an equation means simply to find its coefficients and express them in their lowest
whole numbers.

EQUATIONS (Nuclear)
The shorthand expression of a nuclear reaction.

EQUIVALENCE POINT
The precise point at which all available hydrogen ions ( or hydroxide
ions) have been neutralized is called this.

EQUIVALENT
Abbreviation for 1 gram-equivalent weight.

ESTERIFICATION
One of the most important reactions of both carboxylic acids and alcohols
is their behavior toward each other. In general, a molecule of each can be
expected to react together in such a ware that the elements of water (H and -OH)
are split out between them and an ester forms. This reaction is named esterification.

ESTERS
Esters form by an acid-catalyzed reaction between an alcohol and a carboxylic
acid. Action of water in the presence of an acid catalyst or an enzyme hydrolyzes
esters back to the alcohol and the carboxylic acid. Esters are saponified by action
of hot alkali, which produces the alcohol and the salt of the acid. The ester group
is a feature of molecules of animal fats and vegetable oils.

ETHERS
Ethers, represented by R-O-R', at room temperature are chemically unreactive
toward water, acids, bases, oxidizing agents, or reducing agents. Their molecules
can accept but not donate hydrogen bonds and therefore are more soluble in water
than alkanes of comparable formula weights.

EVAPORATION
Unless a lid is kept on the liquid, however, it may slowly disappear. This change is
called evaporation.

EXERGONIC CHANGE
If the reaction releases energy it is called exergonic.

EXOTHERMIC CHANGE
If only heat energy and no other form of energy is released, the reaction is described
as exothermic.

EXPOSURE
In radiation biology exposure means specifically the dose delivered by X-rays or
gamma rays.

FAHRENHEIT
Its degrees are 5/9 the size of a Celsius degree, and on this scale water freezes
at 32 F and boils at 212F.

FISSION
The disintegration of a large nucleus into smaller fragments with the release of
neutrons, radioactive isotopes, and enormous yields of heat.

FLUIDRAM
3.696 milliliters

FORMALDEHYDE
One of the irritants in photochemical smog, is a gas with a most disagreeable and
distinctive odor. It is used as a germicide and fungicide and, for these purposes, its
common commercial form is a 37 to 40% solution in water (formalin).

FORMULA
Shorthand symbols for compounds.

FORMULA-Molecular
Is the formula of the molecules of a compound without any information about
bonds and structure.

FORMULA-Structural
A formula that displays the network of covalent bonds through the use of
straight lines.

FORMULA WEIGHTS
The sum of the atomic masses of all the atoms whose symbols appear in
a chemical formula is called the formula weight of the substance.

FUNCTIONAL GROUPS
Because the double bond is a structural group that functions chemically, it
is called a functional group.

GALLON (liquid)
4 liquid quarts

GAMMA RAYS
Gamma rays do not consist of particles. Instead, they are a form of energy
similar to powerful X rays.

GASEOUS STATE
A substance in the gaseous state has neither a fixed shape nor a fixed volume.
It takes the shape and volume of whatever container we choose.

GAS TENSION
Gas tension is defined as the partial pressure of a gas over a solution with
which it is in equilibrium when the total pressure is 760 mm Hg. Gas tension
is an indirect measure of how much gas is in solution because the more gas
dissolved in solution the more gas will be above the solution exerting a partial
pressure. A high gas tension means a high availability of the gas from the
solution.

GAY-LUSSAC'S LAW
Joseph Gay-Lussac discover the particular way in which raising the temperature
of a confined gas increases its pressure. According to Gay-Lussac's law: If the volume
of a given weight of gas is held constant, the pressure is directly proportional to the
Kelvin temperature.

GEIGER-COUNTER
When a pulse of radiation creates ions in the tube, a pulse of electricity can flow from
the wire in the tube to the metallicized surface of the tube. This pulse activates a
counting device. The whole apparatus is commonly called a Geiger counter.

GENES
The basic units of heredity.

GENETIC CODE
It is this order of amines or bases that is the genetic code for the genetic message of a
given gene.

GEOMETRIC ISOMERISM
The pair of 2-butenes, which differ only in geometry and not in basic nucleus-to-
nucleus sequence, illustrates geometric isomerism.

GLUCONEOGENESIS
Lactate or pieces of amino acids can be converted to glucose by reactions that in
all but a few steps are the reverse of glycolysis. Gluconeogenesis consumes ATP, but
by salvaging chemical energy in lactate (or amino acids) it reserves the potential for making
much more ATP when the tissue goes back to an aerobic basis. The newly made glucose
may be put into circulation or it may be stored as glycogen or as fat. Via glycogenolysis, stored
glycogen releases when the blood sugar level drops.

GLUCOSE
Glucose, the most important hexose, is found in most sweet fruits, especially
in ripe grapes.

GLUCOSE OXIDASE
Glucose oxidase is an enzyme that catalyzes the oxidation of glucose to its
corresponding carboxylic acid.

GLYCEROL (Glycerin)
Glycerol, a colorless, syrupy liquid with a sweet taste, is freely soluble in water
and insoluble in nonpolar solvents. It is a product of the digestion of simple fats
and oils.

GLYCOGEN
Glycogen is the reserve carbohydrate in animals.

GLUCONEOGENESIS
Meaning the synthesis (genesis) of new (neo) glucose from noncarbohydrate
starting materials.

GLYCOGENOLYSIS
When glycogen reserves are used to release glucose, that reaction is called
glycogenolysis.

GLYCOLYSIS
Glycolysis is the series of reactions that convert glucose (or glucose units from
glycogen) into pyruvic acid (as its negative ion, pyruvate) while generating some ATP.

GRAIN
0.0648 gram = 64.8 milligrams

GRAM
15.43 grains 1 dr ap = 3.887 grams

GRAM-EQUIVALENT WEIGHT
Whatever the acid, its gram-equivalent weight is that amount, in grams, that is
equivalent to (will deliver to a strong base) one mole of hydrogen ion. The gram-equivalent
amount of any base is that amount, in grams, that can be neutralized by one mole of hydrogen
ion.

GRAM-FORMULA WEIGHT
The formula weight of a substance written in grams.

GRAY (Gy)
One joule of energy absorbed per kilogram of tissue.

GROUP (chemical)
The elements in these vertical columns make up chemical families, sometimes
called groups.

GTP (Guanosine triphosphate)
Is a high energy phosphate and it transfers a phosphate unit to ADP to
make ATP.

HALF-LIFE
The half-life is the oldest method for describing the relative stability of a
particular radioactive element. The time that it takes for an initial quantity of
radioactive material to decay to one-half this amount is defined as its half-life.

HARD WATER
Natural water containing hardness ions, Mg2+, Ca2+, or Fe2+ (or Fe3+) precipitates
with ordinary soap, making this water hard to use in washing clothes or other things; hence,
the name, "hard water." To soften any kind of hard water these metallic ions must be
removed, either chemically or by boiling. Boiling works only with temporary hard water
in which the chief negative ion is bicarbonate. Heat breaks down aqueous bicarbonate to
carbonate, which promptly combines with any hardness ions.

HEAT
To make the temperature of an object change, it must be placed in thermal contact with
another object at a different temperature. Eventually the two will attain the same temperature
as the temperature of the colder object rises and that of the warmer object falls. What transfers
to cause these changes is called heat, one of several forms of energy.

HEAT OF FUSION
Most solids, however, change to the liquid state first, when their temperature is raised. This
change, called melting, requires energy called the latent heat of fusion.

HEAT OF VAPORIZATION
The amount of energy per gram required to change a liquid to a vapor or gas is called
its latent heat of vaporization.

HEMIACETALS
These unstable compounds spontaneously revert to aldehydes and alcohols, the
compounds from which they were formed, if efforts are made to isolate them. (Stable
examples are found among carbohydrates.) Hemiacetals are also intermediates in the
hydrolysis of acetals.

HETEROCYCLIC COMPOUNDS
Ring compounds in which all the ring members are not alike are called heterocyclic
compounds.

HOMEOSTASIS
In biochemistry, the analogous behavior is called homeostasis, the behavior of an organism
to some stimulus that tends to off-balance it by responding in such a way as to restore the
system to normal.

HOMOLOG
Butane, for example, is the next higher homolog of propane.

HOMOLOGOUS SERIES
We call such a series of compounds an homologous series because members differ
from each other in a consistent, regular way.

HYDRATES
Many common compounds include intact molecules of water held within the crystals in
a definite ratio to the ions. We call them hydrates, and we properly classify them as
compounds because they obey the law of definite proportions.

HYDRATION
As each ion leave the crystal, it is immediately surrounded by several water molecules. This
behavior, called hydration, is natural since unlike charges attract each other.

HYDROCARBONS
Hydrocarbons are compounds whose members contain only carbon and hydrogen.

HYDROGEN BONDS
When hydrogen is attached covalently to a strong electro-negative element (oxygen, nitrogen,
or fluorine), it has a partial positive charge large enough in a shape small enough to be rather
strongly attracted to an oxygen, nitrogen, or fluorine in some other molecule. This force of
attraction is called the hydrogen bond.

HYDROPHILIC GROUPS
Cell membranes are made of both lipids and proteins. The principal lipids are the
phospholipids, glycolipids, and cholesterol although all three are not present in all
membranes. Molecules of each of these lipids have parts that are either polar or electrically
charged and therefore are attracted to water molecules and attract molecules in turn.
These molecular parts are called hydrophilic groups (hydro-water; philos, loving-"water
loving"). In phospholipids the hydrophilic group is the phosphate ester, partly ionized,
and the attached alcohol, which often includes a substituted ammonium ion.

HYDROPHOBIC PARTS
Membrane lipids all have relatively large hydrophobic parts (hydro, water; phobic, hating-
"water hating"), the hydrocarbon systems. These parts are not attracted to water and cannot
attract water molecules or break into the hydrogen-bonding network of water.

HYPERTONIC
When one of two solutions has a higher osmotic pressure it is said to be hypertonic.

HYPOTHESIS
Soon after putting some "how?" questions to nature, the scientist devises a hesitant,
tentative answer called an hypothesis.

HYPOXIA
Oxygen delivery to active tissues therefore is reduced-a condition called hypoxia ("hypo-"
reduced or lowered or under; "-oxia", oxygen.)

IDEAL GAS
The hypothetical gas that would fit all the gas law equations exactly would be an ideal
gas, to distinguish it from real gases.

INDICATOR
Any dye that will perform the service of indicating the pH of a solution is called an
indicator.

INDUCED-FIT THEORY
As a substrate starts to form noncovalent bonds to the enzyme, strains occur in the enzyme's
noncovalent bonds of its secondary and higher structural features. These features change
according to the induced fit-theory. The shape of the enzyme is induced by the substrate
to alter itself until the fit of substrate over active site is achieved.

INTERNAL ENVIRONMENT
The internal environment consists of all fluids not actually inside cells, and is about
20% of body weight.

INTERNATIONAL SYSTEM OF UNITS (SI)
The International System of Units-in French, Le Systeme Internationale d'Unities and,
hence, the abbreviation SI-the modern form of the metric system.

INTERSTITIAL FLUIDS
Fluids in the interstices or spaces between cells-the interstitial fluids-make up three-
quarters of the internal environment.

INVERSE SQUARE LAW
This inverse square law holds strictly only in a vacuum, but it is close enough when the
medium is air to make good estimates.

INVERT SUGAR
The 50:50 mixture of glucose and fractose that is hydrolyzed is often called
invert sugar.

IODINE NUMBER
The iodine number is the number of grams of iodine that would add to the double
bonds present in 100 g of the lipid.

IODINE TEST
This iodine test can detect extremely minute traces of starch in solution.

IONIC BOND
This net force of attraction between oppositely charged ions that holds the crystal
together is called the ionic bond. It is a strong bond and important in several aspects
of the chemistry of health.

IONIC COMPOUND
Oppositely charged ions aggregate in a ration that insures overall electrical neutrality. The
net force of attraction between them is the ionic bond, a strong bond, and all compounds are
crystalline solids at room temperature. Some ions are polyatomic and are held internally
together by covalent bonds. The charges on monoatomic ions may be predicted from the
electronic configurations of their corresponding atoms as well as from the locations of the
corresponding elements in the periodic chart. That charge is called electrovalence.

IONIZATION
The formation of ions by chemical change.

IONS
Ions are electrically charged particles with sizes on the scale of atoms.

ISOELECTRIC POINT
The value of pH at which no net migration occurs is called the isoelectric point of
the amino acid and is symbolized by pI.

ISOENZYMES
Different proteins in the same individual that have similar if not identical enzymatic activity are
called isoenzymes.

ISOHYDRIC SHIFT
The use of hydrogen ions made in equations 17.3 and 17.4 to drive equation 17.1
from right to left is called the isohydric shift.

ISOMERS
Compunds that have identical molecular formulas but different structures.

ISOMERISM
The phenomenon of the existence of isomers.

ISOPROPYL ALCOHOL
Isopropyl alcohol is a common substitute for ethyl alcohol as a rubbing compound.
It is twice as toxic as ethyl alcohol. Isopropyl alcohol is also used as a disinfectant
in concentrations from 50 to 99%.

ISOTOPE
Atoms of identical atomic number but different masses.

IUPAC SYSTEM (Organic Nomenclature)
Nomenclature in chemistry means the system of names for compounds and
the rules for devising names. The most formal system has been developed over
the last several decades by the International Union of Pure and Applied Chemistry,
and is called the IUPAC System.

KELVIN TEMPERATURE
The SI unit of temperature is the Kelvin (not degree Kelvin, but simply Kelvin).
Its symbol is K. Between the freezing point of water and its boiling point (under
specific conditions) are 100 units of temperature; each one is one Kelvin. On the
Kelvin scale, water freezes at 273.15 K and it boils at 373.15 K.

KERATINS
In hair, wool, animals hooves, nails, and porcupine quills. The keratins are
rich in sulfur.

KETOACIDOSIS
Untreated ketosis, becoming gradually worse, leads inevitably to acidosis-ketoacidosis
to indicate the particular origin.

KETOHEXOSE
A Ketohexose possesses a keto group and a total of six carbon atoms.

KETONE BODIES
Acetoacetate, B-hydroxbutyrate, and acetone build up in the blood-ketonemia-in
starvation and diabetes. These two disorders take so much oxaloacetate for
gluconeogenesis that too little is left to handle via the citric acid cycle the acetyl units coming
from fatty acid catabolism. The excess acetyl units increasingly combine to give acetoacetate
from which the other two ketone bodies are made. Acetoacetate and B-hydroxybutyrate are
normal sources of energy in some tissue.

KETONES
Ketones resemble aldehydes in physical properties. Ketone molecules are of moderate
polarity because of the polarity of the carbonyl group. Their odors are far more pleasant
than those of the aldehydes. The most important chemical property of ordinary ketones is
their general stability toward even strong oxidizing agents.

KETONURIA
The condition of higher than normal concentrations of ketone bodies in urine.

KETOSE
If a keto group, the monosaccharide is a ketose.

KETOSIS
The combined occurrence of ketonemia, ketonuria, and acetone breath is called
ketosis. Unchecked ketosis will lead to a general breakdown and death.

KILOCALORIE (kcal)
The calorie is a very small unit and therefore the kilocalorie (kcal) is more often used.

KILOGRAM (kg)
The SI unit of mass is called the kilogram (kg), defined as the mass of the International
Prototype Kilogram, a block of platinum-iridium alloy kept in the vault at Sevres, France.
No acceptable alternative to this standard has been found, and the kilogram remains as
the only SI reference that could potentially be stolen, lost, or could under corrosion.

KILOMETER
1000 meters (m)

KINETIC ENERGY
A falling rock has energy called kinetic energy by virtue of its mass and its motion. Its kinetic
energy, to be exact, is equal to ? (mass)(velocity)2.

KINETIC THEORY
Because gases are collections of particles (atoms or molecules) in constant, chaotic, random
motion, gas pressure results from the frequency of collisions at container walls per unit
area. Gas temperature is proportioned to the average kinetic energy of the particles in the gas.

LACTIC ACID ACIDOSIS
Hydrogen ions are also produced, and these lower the bicarbonate level in the blood and cause
acidosis, specifically lactic acid acidosis.

LACTOSE (milk sugar)
Lactose occurs in the milk of mammals.

LAW OF CONSERVATION OF MASS
One of the most general features of any chemical change is that the weight of all
reactants equals the weight of all products. So universally has this been experienced
by the scientists that it has become the law of conservation of mass in chemical change:
Mass is neither gained nor lost in a chemical change; mass is conserved.

LAW OF DEFINITE PROPORTIONS
No law of definite proportions applies to mixtures. Stated formally, the law of definite proportions is:
In a given chemical compound the elements are always combined
in the same proportion by weight.
This law, more than any other single statement, defines a chemical compound.

LAW OF MULTIPLE PROPORTIONS
Whenever two elements form more than one compound, the different weights
of one element that combine with the same weight of the other are in the ratio
of small whole numbers.

LAWS OF NATURE
A few hypotheses are on such a grand scale, taking in such a wide variety of
observations, and have been so often checked and found valid, that we call them
laws of nature. A law of nature is quite simply a universal, repeatable experience,
one we have very reason to believe will continue to be true, and one we believe
applies not just to our planet but to our entire universe.

Le CHATELIER'S PRINCIPLE
If some stress is placed on the conditions that affect a dynamic equilibrium,
the system will change in whatever direction will most readily absorb that
stress and bring about a new condition of equilibrium.

LENGTH
The SI unit of length is called the meter.

L-family
"L-" means that this CH2OH is top and right while the ring's oxygen is top and left.

LIGHT ENERGY
The rock may be so hot it glows. Thus if it falls during darkness, it has an
illumination-changing capacity. As it emits light we say that it transmits light energy.

LIPIDS
Are plant and animal substances that will dissolve in ether or similar nonpolar
solvents.

LIQUID STATE
A substance in the liquid state has no fixed shape either, taking whatever shape given
by its container, but a liquid does have a definite volume. Unless a lid is kept on the liquid,
however, it may slowly disappear.

LITER
1000 milliliters (ml)

LOCK-AND-KEY THEORY
With some enzymes binding sites rigidly "match" substrates much as a lock will
accept only one or maybe a few keys. In this "lock-and-key" theory, as the substrate
settles onto these sites, the forces of attraction drawing it down set up strains in the bonds
of the substrate, strains that are the early stags in the reorganization of chemical bonds leading
to products.

LUCITE (plexiglas)
Uses coatings; windows, molded items.

MASS
The mass of an object is defined as the amount of material in it as compared with a reference
standard of mass. The mass of an object is a direct measure of its inertia, meaning its ability
to resist any change in its location, its direction of motion, or its speed of motion.

MATERIAL BALANCE
A material balance is simply the familiar requirement that all atomic nuclei appearing among
reactants also appear somewhere among products.

MEASUREMENT
Scientific data are reported in units provided by the metric system and its successor, the SI. The important units for length are millimeter, centimeter, meter, and kilometer. Those for volume are the milliliter, deciliter, and liter. Commonly used units of mass are the microgram, milligram, gram, and kilogram. Temperature is described in science in units of degrees Celsius or in Kelvins. In medicine units of degrees Fahrenheit are still most commonly used. In describing heat energy, units of calories and kilocalories are most often seen in references for the health sciences. Other kinds of quantities of importance are the density of an object (which numerically is essentially the same as its specific gravity) and its specific heat.

MELTING POINT
The temperature at which the number of particles passing into the liquid state equals the number
returning to the solid is called the melting point.

MENDELEEV, DIMITRI
Dimitri Mendeleev (Russia, 1834-1907) is given the most credit for the development of a periodic chart of the elements.

MERCAPTANS
Sulfur analogs of alcohols are important in the chemistry of proteins. Generically, they are called thio alcohols or mercaptans.

MESOBILIRUBINOGEN
Routine flow of bile brings it to the intestinal tract, where bacterial action converts it to a colorless substance, mesobilirubinogen.

MEMBRANES
A double layer of lipid molecules-phospholipids or glycolipids with cholesterol sometimes also incorporated-comprise the lipid bilayer part of a membrane. The hydrophobic tails of these lipids are lined up side by side within the bilayer away from the aqueous phase of the tissue. The hydrophilic heads poke out into the aqueous medium. On or in the bilayer are the proteins that do all the active work of the membrane and control what gets in or out of the cell. These proteins, energized by other chemical reactions in the membrane, often participate in the active transport of ions or polar molecules against a concentration gradient and through the membrane.

METABOLISM
Metabolism is the continuing chemical activity of all kinds occurring in the body. Not only does it provide the energy for operating nerves, muscles, and the synthesis of biochemical's, it acts also to raise the temperature of the body.

METALLOIDS
Elements on the zig-zag borderline (between metals and nonmetals) are identified, and sometimes they are called metalloids, sometimes semimetals.

METALS
Metals are substances that conduct electricity and that can be polished, drawn into wires, and hammered into sheets.

METHYL ALCOHOL ("Wood alcohol," Methanol)
Most methyl alcohol is made by the reaction of carbon monoxide with hydrogen under extremely high pressure and temperature. It acquired its nickname, wood alcohol, because it is obtainable when wood is heated in the absence of air during the manufacture of charcoal.

Taken internally in sufficient quantity, methyl alcohol produces either blindness or death. It is used primarily as the raw material for the industrial synthesis of formaldehyde, as a solvent, and as a denaturant (poison) for ethyl alcohol.

METHYLCHOLANTHRENE
Methylcholanthrene is another carcinogenic compound isolated from coal tar.

MICROANGIOPATHY
Clinically defined, diabetes is a disorder associated with a blood sugar level that is too much above normal for the existing metabolic situation of the individual and that is accompanied by a relatively specific vascular disease, microangiopathy. Microangiopathy is a change in thickness, composition and metabolism of the basement membrane of blood capillaries. (The basement membrane is the protein support structure encasing the single layer of cells of a capillary.) Microangiopathy is believed to lead to kidney problems, other vascular disorders, and the eye problems of many diabetics. It is most easily observed by opthalmologists during an eye examination.

MICROGRAM
1 milligram = 1000 micrograms

MILK
Milk is an emulsion of butterfat in water with the protein casein acting as the stabilizing substance.

MILK OF MAGNESIA
Indeed, a slurry of magnesium hydroxide in water ("milk of magnesia") is often taken internally as a mild purgative and an antacid.

MILLIEQUIVALENTS (mEq)
The gram-equivalent weight of a substance is usually much too large for convenience in clinical or other analytical work. Solutions being analyzed are normally very dilute. Hence, the smaller unit of milliequivalent, abbreviated meq, is used where 1 Eq = 1000 mEq. A solution that is, say 0.016 N in a substance has a concentration of 0.016 Eq/liter or, easier to say 16 mEq/liter. The milliequivalent weight of a substance is simply its equivalent weight expressed in milligrams.

MILLIGRAM
1 gram = 1000 milligrams (mg)

MILLIMETER
Variation of the meter. 1 centimeter = 10 millimeters (mm)

MILLIMETER OF MERCURY (mm Hg)
The unit of pressure most commonly used in medicine is the millimeter of mercury, symbolized as mm Hg.

MILLILITER (ml)
1 liter = 1000 milliliters (ml)

MILLIREM (mrem)
If an organ receives a 5-millirem dose from a neutron beam and a 10-millirem dose from gamma rays, the total dose equivalent is 15 millirems.

MINERALS
Minerals are metallic and inorganic nonmetallic ions necessary for growth, repair, and operation and which also must be included in the diet.

MINIM
1 fluidram = 60 minims 1 liq oz = 8 fluidrams = 480 minims

MIRROR, silvering of
If the inner wall of the test vessel is clean and grease-free, the silver deposits to form a beautiful mirror, and this reaction is used for the silvering of mirrors. (If the glass surface is not clean, the silver separates as a gray, finely divided, powdery precipitate.)

MITOSIS
When cell division, called mitosis, begins, each chromatin strand may be seen to thicken.

MIXTURE
The components of a mixture do not have to occur together in any particular proportion. The mix of sand, gravel, shells (and trash) at a beach illustrates a mixture. Beaches can still be beaches under varying proportions of these substances. No law of definite proportions applies to mixtures.

MODULATOR
In such a situation the affected enzyme is called a regulatory enzyme or an allosteric enzyme; the chemical that inhibits it is called the modulator or the effector. The phenomenon of affecting a change in an enzyme when a modulator binds at some site other than the catalytic site is called the allosteric effect. ("Allosteric" means "other space" or "other location.")

MOLAR MASS
The formula weight of a substance for written in grams is called its gram-formula weight. Another term growing in popularity is molar mass. The two terms are exact synonyms.

MOLAR CONCENTRATION
The molar concentration of a solution, symbolized by M, is defined as the number of moles of solute per liter of solution. (Note the symbol for mole is mol; for molar concentration, M.)

MOLARITY
The word molarity is a very common synonym for "molar concentration," and it must be added to your vocabulary.

MOLE (mol)
Another term that is commonly used is the word mole, but that term has two (related) meanings. One mole of any substance is that amount equal to its molar mass. That is one meaning; 1
mole = 1 molar mass = gram-formula weight. While the mole is the chemist's unit for amount of substance, it also is a counting unit. One mole of substance X has the same number of formula units as one mole of anything else. By weighing chemicals in ratios according to moles, we obtain them in ratios according to formula units.

MOLECULAR COMPOUNDS
Atoms of most nonmetals (exceptions are the noble gases) can achieve the semblance of outer octets by sharing pairs of electrons in molecular orbitals that form when atomic orbitals partly merge or overlap. The combining ability of a nonmetal, its covalence, may be predicted either from the electronic configuration or the position in the periodic chart of the corresponding element. When atoms of different elements become covalently bound, the bond will likely be polar, the direction of the polarity being predictable by the relative electronegativities. If bond polarities do not cancel, the molecule as a whole will be polar, and neighboring molecules will attract each other. Compounds whose smallest representative samples are molecules with two or more nuclei from different elements are called molecular compounds.

MOLECULAR ORBITALS
A pair of electrons is shared by being in a new kind of orbital, a molecular orbital, which is created when two outer level atomic orbitals from different atoms partially merge or overlap each other. This overlap creates a new space surrounding two (sometimes more) nuclei. In that space reside the shared pair of electrons, and they exist most of the time between the two nuclei, creating an electron density to which the nuclei are attracted.

MOLECULE
A molecule is an electrically neutral particle with two or more atomic nuclei enmeshed in a swarm of enough electrons to make the particle neutral.

MONOD, J.
The discovery that a special messenger RNA was required for enzyme synthesis came from the work of two French scientists, F. Jacob and J. Monod (co-winners of the 1965 Nobel Prize in physiology and medicine with A. Lwoff).

MONOSACCHARIDES
Carbohydrates that cannot be hydrolyzed to simpler molecules are called monosaccharides.

MOSLEY, H.G.J.
H.G.J. Mosley (England 1887-1915) gave us the final form of a periodic law. Periodic law: Many properties of the elements are periodic functions of the atomic number.

MUCIN
One kind of gastric gland secretes mucin that coats the stomach to protect it against digestive juices and acid. Mucin is continually produced and is only slowly digested.

MYCARDIAL INFARCTION
A myocardial infarction is the withering of a portion of the heart muscle following some blockage of the blood vessels that supply it with oxygen and nutrients.

MYOGLOBIN
Myoglobin is an oxygen-holding protein in muscle tissue where it maintains an oxygen reserve and helps transfer oxygen in the tissue.

MYOSINS
Proteins in contractile muscle.

MYXEDEMIA
In an underactive thyroid-myxedema-little radioactivity will be absorbed by the gland.

NEBUTAL
Rapid-acting barbiturate.

NEUTRAL COMMUNICATION
Neutral communication is the work of the nervous system and the signals sent back and forth through it. It provides the basic route of communication between the interior of the body and the signals from the environment received by sight, smell, taste, touch, and hearing.

NEUTRALIZING CAPACITY
The neutralizing capacity or total acidity is the molar concentration of all particles that can neutralize hydroxide ion (or other strong base).

NITROGEN BALANCE
A healthy, adequately nourished person who excretes as much nitrogen per day as he takes by the diet is on a nitrogen balance.

NITROGEN FIXATION
Is the conversion of nitrogen by soil microorganisms into ammonia or ammonia derivatives.

NITROGEN POOL
All amino acids wherever they are found in the body plus other simple nitrogenous substances make up the nitrogen pool.

NONELECTROLYTES
Are nonconductors.

NONMETAL
Nonmetals are poor conductors of electricity.

NORMALITY
The normality of a solution is the number of equivalents of the solute per liter of solution.

NORMAL SOLUTION
In doing calculations with data from titrations, chemists use the more convenient concept of the normal solution, one where we know how many moles of ionizable hydrogen ion there are per liter.

NUCLEAR EQUATION
The shorthand expression of a nuclear reaction is a nuclear equation. To avoid confusing nuclear equations with chemical equations, since they are written very much alike, atomic numbers and weights are shown.

NUCLEIC ACIDS
Deoxyribonucleic acid, DNA, and ribonucleic acid, RNA, belong to the family of polymers called nucleic acids.

NUCLEOTIDES
Their monomer units are called necleotides. Unlike the monomers of other polymers, the nucleotides can by hydrolyzed.

NUCLEUS (Atomic)
Essentially all the mass of an atom is concentrated into an extremely dense particle called the nucleus of the atom. The nucleus contains all the protons and all the neutrons of an atom, all of its subatomic particles except the electrons. The nucleus is a positively charged particle where the amount of charge equals the number of protons.

NUCLEUS (Cell)
The endoplasmic reticulum generally extends from the cell membrane to the wall of the cell nucleus. The nucleus has its own membrane with pores called annuli.

NYLON
One of the first successful condensation polymers was nylon-66, made from hexamethylenediamine and adipic acid.

OCTET (Outer)
The outer octet is usually stable in most environments.

OCTET RULE
The reactions of the reactive atoms of the main groups of the periodic table generally lead to noble gas configurations.

OCTET THEORY
Atoms with noble gas configurations are much more stable than atoms without them. Among the first 20 elements (and many more) their chemical reactions usually tend in whatever direction most directly leads to outer octets (either by taking or giving electrons or by sharing pairs of electrons). The nearer an atom already is to a noble gas configuration the more reactive it tends to be. Metals generally donate electrons completely and become ions. Nonmetals will act as electron acceptors if presented to metals but as electron sharers if given other nonmetals.

OLEIC ACIDS
Oleic acid is the most abundant and most widely distributed fatty acid in nature.

OPTICAL ACTIVITY
Molecules of all carbohydrates possess "handedness." Each kind can exist in a mirror image form with which it is not super imposable. Such isomers are called optical isomers. Toward reagents whose ions or molecules have some symmetry (i.e., are super imposable on their own mirror images), optical ionomers show no difference in chemical behavior. However, toward substances that possess "handedness," as all enzymes do, optical isomers show remarkable chemical differences. Humans can metabolize one optical isomer of glucose, fructose, or galactose but not their mirror images.

OPTICAL ISOMERISM
This general phenomenon of having isomers that differ only in their "handedness" is called optical isomerism.

OPTICAL ISOMERS
D- and L-glucose are called optical isomers.

ORGANIC CHEMISTRY
Organic chemistry is the study of the structures and properties of the compounds of carbon.

ORGANIC COMPOUNDS
All organic compounds contain carbon. In addition, all but a small handful of organic compounds also contain hydrogen.

ORGANOHALOGEN COMPOUNDS
The simplest organohalogen compounds are those in which one or more halogen atoms have replaced hydrogen's of hydrocarbons.

OSMOSIS
If two solutions of different particle concentrations are separated by an osmotic membrane, osmosis will occur, the migration of solvent from the solution that is less concentrated to the one that is more concentrated in solute.

OUNCE
1 ounce = 16 drams (dr avdp) and 1 ounce = 8 drams (dr ap)

OXIDASE
An oxidase is an enzyme catalyzing an oxidation.

OXIDATION
The loss of electrons is called oxidation.

OXIDATION NUMBERS
The oxidation number of an element is the size and kind of electrical charge its ions can bear.

OXIDATIVE DEAMINATION
The amino group of glutamic acid can be removed by a combined oxidation and hydrolysis in a
reaction called oxidative deamination.

OXIDES
Compounds of metals or nonmetals and oxygen are called oxides.

OXIDIZING AGENT
Whatever loses electrons is said to be oxidized; what gains electrons is reduced. Whatever causes an oxidation is called an oxidizing agent.

OXYGEN (Partial Pressure)
Partial pressure is the particular contribution each gas makes to the total pressure. The partial pressure of the gas is the pressure its quantity would alone exert if it were the only gas in the container.

OXYGEN DEBT
When a tissue operates anaerobically, its lactate level rises and it is in a condition of oxygen debt.

OXYHEMOGLOBIN
The combined action of hydrogen ion and carbon dioxide to make it easier for oyhemoglobin to give up oxygen is called the Bohr effect.

OZONE
Ozone is a special form of oxygen and one of the most powerful oxidizing agents known. It destroys vegetation and seriously affects the respiratory tract.

PAN
PAN is the name for a family of organic nitrates.

PARAFFINS
Because of the general inertness of the alkanes, they have been nicknamed "paraffins," from the Latin parum, little; affinis, affinity. Ordinary household paraffin is a mixture of alkanes having about 20 carbons per molecule.

PARKINSON'S DISEASE
An interesting sidelight involving DOPA (dihydroxyphenylalanine) is the fact that the level of its corresponding amine, dopamine, in the brain is reduced in Parkinson's disease.

PARTIAL PRESSURE
The partial pressure of the gas is the pressure its quantity would alone exert if it were the only gas in the container.

PENICILLIN
The cell has worked hard, spent a great deal of chemical energy, and used considerable material-only to have molecules of penicillin inhibit this final, crosslinking step. The cell, not properly formed, cannot last, and the spread of the bacterial infection is halted.

PENTOSE PHOSPHATE PATHWAY
Glucose may be catabolized through pentose intermmediates to make NADPH, instead of ATP. The NADPH is used when some biosynthesis of a macromolecule requires a reducing agent.

PEPSIN
A third gastric gland secretes a protein-digesting enzyme, pepsin, in an inactive form called pepsinogen.

PEPSINOGEN
Pepsinogen does not need a cofactor to be activated and it therefore cannot be called an apoenzyme. Instead, it becomes pepsin by a small degradation of its polypeptide system that exposes its active site.

PEPTIDE BOND
The amide bond, carbonyl-to-nitrogen, is the chief covalent bond that forms when proteins are put together. In protein chemistry this bond is called the peptide bond, and the protein polymer is called a polypeptide.

PERIOD, chemical
The resulting arrangement of the elements is called the periodic table. Each row is called a period.

PERIODIC LAW
Many properties of the elements are periodic functions of the atomic number.

PERIODIC TABLE
The resulting arrangement of the elements is called the periodic table.

PEROXYACYL NITRATES (PAN)
PAN is the name for a family of organic nitrates, the peroxyacyl nitrates.

PERSPIRATION
In perspiration liquid water changes to vapor, a change that leaves the skin (or lungs) a little cooler than it otherwise would be.Perspiration may be sensible or insensible, that is, it may be obvious and noticeable as when beads of sweat form; it may be not obvious and not noticeable.

PETROLEUM
Petroleum (petra, rock; oleum, oil) is a complex mixture of organic compounds of which nearly all are hydrocarbons.

PHENYLKETONURIA, or PKU
In phenylketonuria, or PKU one defective gene results in the absence of an enzyme needed to convert the amino acid phenylalanine to tyrosine. As a result another metabolic event occurs to phenylalanine more frequently than normal, its conversion to phenylpyruvic acid. This keto-acid (rather, its negative ion) builds up in the bloodstream, and since it is a ketone that has a phenyl group, the condition is called phenylketonemia.

PHOSPHOGLYCERIDES
The principal phosphoglycerides incorporate into their molecules units of choline, ethanolamine, or serine to give phosphatidylcholine (lecithin), 2, phosphatidylethanolamine, 3, and phosphatidylserine, 4. As the structures of 2 to 4 show, one part of each phosphoglyceride molecule is very polar, having electrically charged sites. The remainder is nonpolar and hydrocarbonlike. These characteristics have important implications in understanding how phosphoglycerides are used to make cell membranes.

PHOSPHOLIPIDS
Phospholipids are esters either of glycerol or of sphingosine, a long-chain dihydric amino alcohol with one double bond.

PHOTOSYNTHESIS
The conversion of solar energy by plants into chemical energy in plant substances is called photosynthesis.

PHYSICAL CHANGE
A physical change is any other event in which new compounds (or original elements) are not produced. Physical changes alter forms, not materials.

PHYSICAL PROPERTY
A physical property is any feature we can observe and measure without changing the material into a different chemical substance.

PHYSIOLOGICAL SALINE SOLUTION
A solution 0.9% in sodium chloride has an osmotic pressure equal to that exerted by the solution made inside red cells. Red cells bathed in this solution, called physiological saline solution, under neither hemolysis nor crenation.

PINOCYTOTIC VESICLES
Pinocytotic vesicles are a part of the way a cell can move materials to the outside of the cell.

PINT
1 liq pint - 16 liquid ounces = 2 cups = 4 gills

PLASMA, Blood
One kilogram of blood plasma has about 80 grams of proteins-albumins, globulins and fibrinogen.

PLASMALOGENS
Plasmalogens are another family of glycerol-based phospholipids, and are widely distributed in the membranes of nerve cells and muscle cells. They differ from the other phosphoglycerides in having an unsaturated ether link instead of an acyl unit at one end of the glycerol unit.

PLASTER OF PARIS
Plaster of Paris, for example, although not completely anhydrous, contains relatively less water than gypsum. If we mix plaster of paris with water, it soon sets into a hard crystalline mass.

B-PLEATED SHEET
Pauling and Corey also discovered that molecules in some proteins line up side by side, becoming regularly pleated as they do, to form a sheet like array.

POISONS
Irreversible inhibition of enzymes is accompanied by poisons that bind to the active site or the binding sites or otherwise distort the shape of the enzyme.

POLAR BOND
A covalent bond with a partial positive charge at one end and a partial negative charge at the other is called a polar bond.

POLAR MOLECULES
Polar bonds may or may not make the molecule polar. Another useful way of thinking about polar molecules is to observe that in them the geometric enter of all positive charges does not occur at the same place as the geometric center of all negative charges.

POLYMER
A polymer is a very-high-formula-weight substance whose structure consists of many repeating units or parts ("polymer" from the Greek poly-, many; meros, parts).

POLYMERIZATION
A polymer is a very-high-formula-weight substance whose structure consists of many repeating units or parts. We make one by letting its unit parts, as separate molecules or monomers, react with each other to link together successively, many, many times. This event is called polymerization.

POLYPEPTIDE
The protein polymer is called a polypeptide.

POLYSACCHARIDES
Starch and cellulose are common polysaccharides.

POTENTIAL ALDEHYDE GROUP
The hemiacetal linkage (one carbon, boldfaced, carrying both an alcohol and an ether linkage) occurs in several of the nutritional important sugars. It is often called a potential aldehyde group and glucose possesses one.

POUND
1 pound = 16 oz (oz avdp) 1 pound = 12 ounces (oz ap) = 5760 grains

PRESSURE
Pressure is defined as force per unit area.

PRIMARY (1?) ALCOHOL
A primary (1?) alcohol is one in which the alcohol carbon atom carries only one carbon-to-carbon bond.

PRIMARY STRUCTURE
All protein molecules have the repeating sequence in their molecular "backbones." This repeating sequence, together with the sequence of side chains, constitutes the primary structure.

PRODUCT
A chemical property is any one of the chemical reactions the substance can undergo. As the reaction proceeds we usually notice that the physical properties of the original material's called the reactants disappear. New physical properties appear, those of the substances that form called the products of the reaction.
PROSTAGLANDINS
The prostaglandins are a family of modified fatty acids that have hormonelike activity but that, unlike hormones, occur in nearly all tissues and organs. Exactly how they work is not known nearly as well as what they do.

PROSTHETIC GROUP
Nonpolypeptide molecules associated with proteins are called prosthetic groups.

PROTEINS
A protein is a molecular species consisting mostly or entirely of amino acid residues and held together in a particular overall shape by both covalent forces and noncovalent forces. Some proteins consist entirely of single polypeptide chains, or two or more such chains in a quaternary structure. Other proteins are made of chains bound to nonprotein groups (a prosthetic group). Because of acidic and basic side chains, the solubility of a protein is sensitive to the pH of the medium and is least at the pI or isoelectric point of the protein. Because of the peptide (amide) bonds, proteins can be hydrolyzed (digested). Because of noncovalent forces are individually week, proteins can be denatured, suffering the loss of 2?, 3? and 4? structural features.

PROTON
A proton has one positive unit of charge, 1+. A proton can attract an electron; anything positively charged can attract anything else negatively charged. A proton will repel another proton.

PROTOPLASM
Everything inside the cell has the general name of protoplasm.

PYRIDOXAL
Pyridoxal, an aldehyde, is made from vitamin B6 (pyridoxine), by the oxidation of a -CH2OH group.

PYRIDOXAL PHOSPHATE
Phyridoxal phosphate, the phosphate ester of pyridoxal, is a coenzyme needed in those reactions in which amino groups are transferred.

QUART
1 liq quart = 2 liquid pints 1 liq quart = 946.4 milliliters

RAD
The unit is called the rad(D), after radiation absorbed dose, and by definition of a dose of 1 rad has been absorbed if the tissue has received 100 ergs of energy per gram.

RADIATION
Any warm object radiates energy similar to light energy. It is called either infrared radiation or thermal radiation. Unlike light, it is invisible.

RADIATION (Ionizing)
The source of danger to living things posed by radiations is their ability to generate strange, unstable, highly reactive ions as they plow through living tissue. Because of this ability atomic radiations and x-rays are called ionizing radiations. The most serious damage from ionizing radiations is within the nuclei of living cells where chemical changes to deoxyribonucleic acid (DNA) may occur.

RADIATION SICKNESS
Should enough cells die in healthy tissue, it may lead to death or radiation sickness, a series of symptoms such as nausea, vomiting, drop in white cell count, diarrhea, dehydration, prostration, hemorrhaging, and loss of hair.

RADIOACTIVITY
Atoms of radioactive isotopes have unstable nuclei that decay bit by bit to more stable isotopes of other elements. Radioactive decay releases alpha or beta rays, often accompanied by gamma rays, as the radioactive disintegration series is descended.

RADIOIMMUNOASSAY
Radioimmunoassay is a method for measuring the concentration of some substance by letting its molecules compete with their radioactively labeled forms in forming an antigen-antibody complex.

RANCIDITY
When fats and oils are left exposed to warm, moist air for any length of time, they become rancid, meaning that they generate disagreeable flavors and odors. Two kinds of reactions are chiefly responsible, hydrolysis of ester links and oxidation of double bonds.

REACTANT
A chemical property is any one of the chemical reactions the substance can undergo. As the reaction proceeds we usually notice that the physical properties of the original material's called the reactants disappear.

REACTIONS, Chemical
Chemical reactions involve rearrangements or redistributions of electrons relative to atomic nuclei and are best symbolized by balanced chemical equations. The coefficients of such an equation represent the combining proportions by particles, not by weight.

REDOX REACTIONS
Reactions of electron transfer are called oxidation-reduction reactions or simply redox reactions.

REDUCING AGENT
What causes a reduction is called a reducing agent.

REDUCTION
The gain of electrons is called reduction.

REM
One rem of any given radiation is that quantity of radiation that causes damage equivalent to the absorption of 1 roentgen. (The name "rem" comes from roentgen equivalent for man.) Dose equivalents in rems are addictive, regardless of kind of radiation responsible.

RENAL THRESHOLD
The blood sugar level above which the kidneys can no longer reabsorb all the blood sugar and keep it in the bloodstream is called the renal threshold.

RENIN
If blood pressure drops (as in hemorrhaging) the kidneys secrete a trace of renin, an enzyme, into the blood. Renin acts as one of the globular proteins in blood, angiotensinogen (a proenzyme) to convert it to another enzyme, angiotensin I.

REPLICATION, DNA
Through DNA replication the genetic message of the first cell is passed to each of the two new cells.

RESID
The residues that do not distill are used as residual fuel oil ("resid") or made into asphalt and coke.

RESPIRATORY CHAIN
The term respiratory chain has two meanings: a sequence of reactions, and a team of the enzymes for these reactions. These enzymes are organized mainly in tiny particles called mitochondria that occur by the hundreds and thousands inside cells. The respiratory chain has two main sequences; first the H:- and H+ from enzyme to enzyme until finally one is reached that catalyzes the reduction of oxygen to water, and second, the tapping of the energy flow in this sequence to make ATP.

RETINOPATHY
Diabetic microangiopathy in the retina of the eye, called diabetic retinopathy, is the second most common cause of blindness in the United States and is the leading cause of new cases of blindness among adults. Diabetic retinopathy can be detected in adults before abnormalities in sugar metabolism surface.

RIBONUCLEIC ACIDS (RNA)
Nucleic acids are either based on ribose, in which case they are called ribonucleic acids, abbreviated RNA.

ROENTGEN (R)
In radiation biology exposure means specifically the dose delivered by X rays or gamma rays. The unit of exposure is called the roentgen, symbolized by R, after Wilhelm Roentgen (1845-1923), the discoverer of X rays and winner of the 1901 Nobel Prize in Physics.

SALICYLATES
Sodium salicylate and especially acetylsalicylic acid (aspirin) are widely used. Methyl salicylate is used in liniments. Phensylsalicylate has been used in ointments that protect the skin against ultraviolet rays.

SALICYLIC ACID
Salicylic acid can function either as an acid or as an alcohol (more correctly, a phenol) since it possesses both functional groups. Salicylic acid, its esters, and its salts, taken internally, have both an analgesic effect (depressing sensitivity to pain) and an antipyretic action (reducing fever). As analgesics, they act to raise the threshold of pain by depressing pain centers in the thalamus region of the brain. Salicylic acid, itself, is too irritating to be used internally.

SALT BRIDGE
The resulting force of attraction in a protein is called a salt bridge.

SALTS
Unlike acids or bases, no simple generalization can be made about the properties of salts. A few rules help to organize a mass of data about their solubility. Salts can be prepared from the reaction of an acid with a metal, a metal hydroxide, a metal bicarbonate, or carbonate, or they can be produced by a double decomposition (change of partners), a reaction between two salts in solution.

SAPONIFICATION
The saponification of an ester is merely a slight variation of ester hydrolysis. The term saponification comes from the Latin sapo onis, or "soap + fy"; that is to make soap. Ordinary soap is a mixture of sodium salts of long-chain carboxylic acids.

SATURATED COMPOUNDS
Those whose molecules have only single bonds are saturated compounds.

SCIENTIFIC METHOD
Ideas for new experiments emerge. The hypothesis is revised as needed or rejected, and a new one is tried. This pattern of activity can be seen in so many success stories in science that we have come to call it the scientific method.

SCINTILLATION COUNTER
Scintillation counters are devices that include a surface coated with a special substance that gives off a tiny light flash when it is hit by a radiation.

SECONDARY CARBON
In the sec-butyl group this carbon is directly attached to two other carbons and is therefore classified as a secondary carbon.

SECONDARY STRUCTURE
Once a cell puts together a long protein molecule, noncovalent forces of attraction between parts of the structure make it twist into a particular shape called its secondary structure.

SEDATIVE, Barbiturates as
These amidelike compounds are the best known, the most widely prescribed, and the most frequently abused members of a family of drugs that act as sedatives. In properly supervised doses, they mildly depress the central nervous system and cause both breathing and heart beat to slow down.

SEMIMETALS
Elements on the zig-zag borderline (between metals and nonmetals) are identified, and sometimes they are called metalloids, sometimes semimetals.

SGOT
The level in serum of another enzyme nicknamed SGOT (for glutamic oxaloacetic transaminase in serum) also rises in viral hepatitis.

SHOCK, TRAUMATIC
In trauma such as sudden severe injury, major surgery, or extensive burns capillary walls become more permeable to proteins. These leak into interstitial spaces and the colloidal osmotic pressure of blood drops. Interstitial fluid then cannot dializye back into the bloodstream as effectively, and the blood volume quickly drops. Oxygen transport is impaired. The individual goes into traumatic shock. The loss of blood volumes causes it; therefore, the restoration of blood volume is mandatory to control it.

SI
The International System of Units - in French, Le Systeme Internationale d'Unities and, hence, the abbreviation SI-is the modern form of the metric system.

SMOG
Sulfur trioxide is made in smoggy air by the slow oxidation of the dioxide. Because sulfuric acid is a strong acid, the presence of sulfur trioxide in smog is a serious situation affecting both health and materials.

SOAP
Ordinary soap is a mixture of sodium salts of long-chain carboxylic acids.

SOLAR ENERGY
All energy for living ultimately comes from the sun. Whether we think of the warmth it gives to our atmosphere, or of the water it makes possible through evaporation and precipitation for crops, power, and satisfying our thirst, or of the food-bearing plants it helps grow, we realize our dependence on solar energy. Solar energy pours into our planet, free of charge, at a rate of about 1.3 x 10?? kilocalories per year. The clouds reflect approximately 40% of this energy back into space. Just about all of the rest is also eventually radiated back. Otherwise the planet would become hotter and hotter. But we use some of it first. Its warmth keeps most of the planet inhabitable, and about 0.04% of the received solar energy enters into metabolism in the biosphere-the thin layer of our planet within which any form of life operates. Green plants from microscopic, marine phytoplankton to towering forest giants accept that energy and make the molecules on which all animals depend for both their materials and chemical energy.

SOLID STATE
A substance in the solid state has both a fixed shape and volume.

SOLUBILITY
The solubility of a compound is usually expressed in the number of grams that can be dissolved in 100 grams of the solvent. Factors that affect solubility are temperature and pressure, but pressure affects only the solubilities of gases, not of liquids or solids.

SOLUBILITY "SWITCH"
The carboxyl group is one of nature's major solubility "switches." Through it we switch on or off the solubility of a substance merely by adjusting the pH of the medium.

SOLUTE
Materials dissolved in a solvent are called solutes.

SOLUTIONS
Small ions or molecules form solutions-homogeneous mixtures that do not separate spontaneously nor are separable by filtration. If the solute is ionic, an aqueous solution will conduct electricity. Regardless of the chemical identities of solute particles, in proportion to their concentrations in a fixed amount of solvent they can cause it to undergo osmosis under suitable conditions.

SOLVATION
A more general term, solvation, applies to any solvent including water.

SOLVENT
The substance into which something is dissolved is called the solvent.

SPECIFIC GRAVITY
Specific gravity is related to density, but it is defined as the ratio of the mass of an object to the mass of an equal volume of water at the same temperature. Since the density of water in g/ml (and rounded) numerically equals 1 over the range of temperatures we normally experience, dividing the density of some object by the density of water is the same as dividing by 1, as far as the numbers are concerned. The units, however, cancel and specific gravity has no units. Numerically the specific gravity of an object will be so close to its density that we usually say they are numerically the same.

SPECIFIC HEAT
The amount of heat that will change the temperature of specifically one gram of a substance by one degree Celsius is called specific heat (or specific heat capacity, or heat capacity).

STANDARD ATMOSPHERE OF PRESSURE
The SI unit of pressure is called the pascal (Pa). It compares with the millimeter of mercury as follows: 1 mm Hg = 133.3224 Pa. This makes the standard atmosphere equal to 101 325.024 Pa or approximately 101 kilopascals (kPa). While most professional organizations are officially promoting the switch from mm Hg to kPa for reporting pressures of respiratory gases, few clinical laboratories have made the change. The "mm Hg" remains the most widely used unit in medicine for this purpose. The situation could eventually change, and you should be aware of that possibility.

STANDARD SOLUTION
If the "unknown" is an acid, a standard solution (that is, one whose concentration is accurately known) of a strong base is added to the unknown from a buret until the indicator color just barely changes.

STARCH
This nutritionally important polysaccharide is a polymer of a-glucose. Some of its molecules are in an unbranched chain-amylose-and others in a branched network-amylopectin. Acetal oxygen bridges join the glucose units together, and humans have an enzyme that can catalyze the hydrolysis (digestion) of starch.

STEROIDS
These nonsaponifiable lipids all have the unique steroid nucleus of four fused rings. Several steroids are sex hormones, and oral fertility control drugs mimic their structure and functions. Cholesterol, the raw material used by the body to make other steroids, is also made by the body. If its synthesis or delivery is upset, cholesterol can be a problem in the bloodstream.

STRUCTURAL FORMULAS
A formula that displays the network of covalent bonds through the use of straight lines is called a structural formula.

SUBSTRATE
Many enzymes are named by attaching the suffix -ase to the name of the compound, called the substrate, whose reaction the enzyme catalyzes.

SUCROSE
Sucrose (Cane sugar, beet sugar, table sugar) The juice of sugar cane contains about 14% sucrose. Sugar beets have about 10 to 16% sucrose. Much of our supply of sucrose now comes from sugar beets, and so-called beet sugar and cane sugar are indistinguishable. White sucrose is probably the purest single organic compound known that is so widely and inexpensively sold.

SULFUR DIOXIDE
Sulfur dioxide arises from the combustion of sulfur or the roasting of sulfide ores in air.

SUPERSATURATION
An interesting situation arises if we cool a saturated solution that is not in contact with any crystals to which dissolved ions can return. Nothing visible may happen! The "excess" solute may remain in solution. This state is not stable, since a dynamic equilibrium is not present, and the solution is now supersaturated. If we add a "seed" crystal of the solute to a supersaturated solution, often a swift and dynamic separation of solute occurs. The "seed" provides a surface onto which solute can crystallize.

SURFACE ACTIVE AGENTS
Any substance that will lower water's surface tension is called a surface active agent, or a surfactant. Using the analogy of the thin, elastic surface membrane, a surfactant cuts that membrane to ribbons.

SURFACE TENSION
Surface tension is a phenomenon in which the water behaves as if it were a thin invisible, elastic membrane. Dust that is actually more dense than water can be made to float because of this "membrane."

SURFACTANT
Any substance that will lower water's surface tension is called a surface active agent, or a surfactant. Using the analogy of the thin, elastic surface membrane, a surfactant cuts that membrane to ribbons.

SUSPENSION
Clay shaken in water, for example, forms a suspension, a mixture that is filterable, unstable with respect to settling, and nontransparent.

TABLESPOON
1 tablespoon = 3 teaspoonfuls = 250 ml

TEASPOON
1 teaspoon = 5 ml

TEMPERATURE
The SI unit of temperature is the Kelvin (not degree Kelvin, but simply Kelvin). Its symbol is K. Between the freezing point of water and its boiling point (under specific conditions) are 100 units of temperature; each one is one Kelvin. In an older system called the Celsius scale, each of these units is called one Celsius degree. One Celsius degree equals one Kelvin, exactly.

TERTIARY ALCOHOL
A primary (1?) alcohol is one in which the alcohol carbon atom carries only one carbon-to-carbon bond. In a secondary (2?), the alcohol carbon atom carries two and only two carbon-to-carbon bonds; in a tertiary (3?) alcohol it carries three.

TERTIARY CARBON
In the t-butyl group this carbon has direct bonds to three other carbons and is classified as a tertiary carbon.

TERTIARY STRUCTURE
The final shape of the polypeptide, its tertiary structure, thus emerges in response to simple molecular forces, to water-avoiding and water-attracting properties of the side chains.

TETRAHEDRAL CARBON
We therefore call any carbon having four single bonds, a tetrahedral carbon, and the angle between any two covalent bonds at a tetrahedral carbon is 109.5?.

THRESHOLD
There is no threshold, no minimum level of exposure below which no damage will occur.

THYROXINE
Thyroxine affects several enzyme systems, including the activities of some involved in the oxidation of glucose. To replace the glucose some glycogenolysis occurs.

TRACE ELEMENTS
Others, called the trace elements, are required in very small amounts. In large quantities, they are poisons, yet in traces they are essential to health. Thus it is not so much what one takes into the body, but how much.

TRANSAMINATION
A number of other amino acids can transfer their amino groups to a-ketoglutarate in a complex reaction called transaminatin, equation 20.1.

TRANSGLUCOSIDASE
For glucose transfer.

TRANSLATION (genetic)
Translation is mRNA-directed synthesis of a polypeptide.

TRANSMUTATION
The atom's electrons make necessary adjustments, and different elements form. Radioactive decay, therefore, is accompanied by the transmutation of an element, the change of one element into another.

TRANSPHOSPHATASES
Often called kinases, help transfer a phosphate unit from one molecule to another.

TRIPLE BOND
In other molecules three pairs of electrons must be shared to create the net effects of outer octets. The resulting bonds are called triple bonds, and examples are nitrogen and acetylene.

TRYPSINOGEN
Enterokinase, from intestinal juice, activates trypsinogen. Besides catalyzing the digestion of polypeptides in chyme, trypsin activates the other proteolytic enzymes.

TYNDALL EFFECT
Colloidal particles are large enough to reflect and scatter light, and colloidal dispersions in water exhibit a phenomenon known as Tyndall effect.

UREASE
Urease is an enzyme that approaches absolute specificity. It catalyzes the hydrolysis of the amide bonds in urea, but not in such closely similar compounds as biuret or amides in general.

UREMA
If the kidneys cannot perform these services because of injury or disease, the wastes of acidosis and nitrogen metabolism build up in the blood, a condition called urema or uremic poisoning.

URINOMETER
The float is called a hydrometer in general and a urinometer when its scale is marked for the measurement of urine.

VAPOR PRESSURE
At any temperature the space above the surface of a liquid contains molecules that have evaporated from the liquid. These make their own contribution to the total pressure of the atmosphere immediately above the liquid in accordance with Dalton's law. We call that contribution the vapor pressure of the liquid if it is measured under conditions in which the number of molecules that are escaping into the vapor state equal the number returning to the liquid state (i.e., under conditions of equilibrium between liquid and vapor state). The higher the temperature of a liquid the higher its vapor pressure. Vapor pressure may be thought of as a measure of the escaping tendency of the liquid.

VASCULAR COMPARTMENT
All the veins and arteries together are called the vascular compartment.

VENTILATION
Ventilation itself is the circulation of air into and out of the lungs.

VIRUSES
These packages of DNA or RNA in a protein overcoat can take over metabolic and genetic apparatus in their host cells. Some are implicated in cancer.

VOLATILE LIQUID
Liquids that evaporate quickly at room temperature are described as volatile liquids. (Anesthetic ether, for example, is extremely volatile.)

WATER
Because bonds in the water molecule are very polar and make an angle of about 104? with each other, the molecule is very polar. Water's polarity accounts for its unusual specific and latent heats, its high surface tension, and its ability to dissolve ionic and polar molecular substances. Water reacts chemically only very slowly with most substances unless a catalyst is present to lower the energy of activation.

WEIGHT
The weight of an object is a measure of how much it is attracted by gravity.

XRAYS
X rays are synthetic. In radiation biology exposure means specifically the dose delivered by x rays or gamma rays. The unit of exposure is called the roentgen. The more energy in a beam of x rays or gamma rays the more ions will be produced in the air through which the rays travel.

YARD
1 yard = 3 feet

ZYMOGENS
Some other protein-digesting enzymes are secreted in inactive forms, and these forms in general are called zymogens.

ACID
Substance that produces hydrogen ions when dissolved in water; the hydrogen may be replaced by metals or bases.

ACTIVATION ENERGY
Energy that must be supplied to reactants before a reaction can take place.

ALCHEMY
The forerunner of modern chemistry, alchemy mixed magic and mysticism with a genuine curiosity in the nature and properties of materials.

ALCOHOL
Organic compound with one or more hydroxyl (-OH) groups.

ALDEHYDE
Organic compound, such as formaldehyde, that contains the CHO group.

ALIPHATIC COMPOUND
Organic molecule consisting of straight or branched carbon chains.

ALKALI
Solution of a base (usually the oxide of a metal) in water; contains hydroxide ions and reacts with an acid to produce salt and water.

ALKALI METALS
Highly reactive elements of group 1 of the periodic table, e.g. sodium, potassium

ALLOTROPES
Different physical forms of the same element.

ALLOY
Mixture of two or more metals, e.g. brass (copper and zinc).

ALPHA RADIATION
Emission of alpha particles (two protons and two neutrons) from the nucleus of a radioactive atom.

AMALGAM
Alloy of mercury with other metals

AMORPHOUS
Describes substance lacking crystalline structure.

AMPHOTERIC
Describes substance with both alkaline and acidic properties.

ANALYTICAL CHEMISTRY
Branch of chemistry concerned with the composition of substances.

ANION
Negative ion, attracted to anode in electrolysis.

ANODE
Positive electrode, attracted to the anion in electrolysis.

ASSAY
Quantitative chemical test to determine composition of a substance.

ATOM
Smallest unit of an element that has properties of that element and can take part in a chemical
reaction.

ATOMIC MASS
Mass of one atom of a particular element measured in atomic mass units.

ATOMIC NUMBER
This is equal to the number of protons in the nucleus of the atom of a particular element.

ATOMIC STRUCTURE
Structure of an atom in terms of the number and arrangement of its constituent protons, and electrons.

ATOMIC THEORY
Theory that all matter is made up of atoms.

BASE
Substance that reacts with an acid to produce a salt; most are oxides of metals.

BASE METAL
Metals (e.g. copper) that lose luster on exposure to air.

BETA RADIATION
Emission of beta particles (electrons) from the nucleus of a radioactive atom.

BOND
Force holding together tow atoms, ions or molecules, or mixture of these. Bonds are formed or broken during chemical reactions.

BOND ENERGY
Energy required or released when covalent bond is formed, or energy required to break covalent bond.

CATALYST
Substance that speeds up a chemical reaction, but which itself is not changed.

CHEMICAL CHANGE
Change through which new substances are produced.

CHEMISTRY
Study of composition of substances, and the changes in composition that they undergo in certain conditions.

CHROMATOGRAPHY
Technique used for separating mixed soluble substances. A solution of mixed substances poured through an absorbent material creates different bands of substances which are absorbed at different rates. The solvent is collected in a beaker.

COLLOID
Substances, usually dispersed in liquid form, so that the molecules are not separated, as in a solution, but are grouped together and visible under the microscope, e.g. milk.

COMBINATION
Joining of two or more substances by chemical bonds to form a compound.

COMBUSTION
Chemical reaction in which heat is produced.

COMPOUND
Substance made of two or more elements joined together. It can be decomposed by chemical action into simpler substances.

CONDENSATION
The change of a vapor to a liquid, or a type of reaction where two organic molecules combine with the elimination of water.

CONDENSER
Device for condensing vapor into liquid.

CORROSION
The eating away of a substance by moisture and/or chemicals.

COVALENCY
Measure of ability of atom to form covalent bonds.

COVALENT BOND
Bond formed between atoms by sharing electrons.

CRYSTAL
Solid substance with atoms arranged in a regular polyhedral pattern.

CRYSTALLIZATION
Formation of crystals in solution of crystalline substance.

DECOMPOSITION
Breaking down of a compound into simpler substances.

DECREPITATION
Crackling sounds produced when crystals explode on heating.

DEHYDRATION
Process of removing water from a substance.

DELIQUESCENT
Describes substances which absorb sufficient water from the air to make a solution, e.g. sodium hydroxide.

DIFFUSION
Spreading out of liquid or gas caused by random movement of its molecules.

DISSOCIATION
Reversible separation of compound into simpler components, e.g. sodium chloride into sodium ions and chloride ions.

DISSOLVE
To mix gas or solid with a solvent to produce a solution.

DISTIL
Process of changing liquid to vapor by heating, then condensing vapor back to liquid.

DISTILLATION
The act of boiling a liquid while condensing and recovering the resulting vapor. Distillation is used to purify or separate liquids.

EFFERVESCENT
Describes substances which when placed in a liquid causes vigorous release of small gas bubbles, e.g. sodium hydrogen carbonate in water.

ELECTROLYSIS
Chemical decomposition caused by passage of electricity through an electrolyte solution, e.g. electricity through water creates gas bubbles of hydrogen at the negative cathode and oxygen at the positive cathode.

ELECTROLYTE
Substance which, dissolved in water, will conduct electricity.

ELECTRON
Subatomic particle with a negative charge.

ELECTROVALENCY
Measure of ability of atom to form ionic bonds.

ELEMENT
Substance which cannot be broken down into simpler substances by chemical means.

EMULSION
Colloidal dispersion of one liquid in another, e.g. milk, paint.

ENDOTHERMIC REACTION
Reaction where heat energy is taken in.

EVAPORATE
To heat liquid below boiling point so that vapor is given off.

EVAPORATION
Process of turning liquid into vapor below the boiling point of the liquid.

EXOTHERMIC REACTION
Reaction where heat energy is released.

EXPLOSION
Very rapid reaction which releases much energy, and large volumes of gases, heat and light.

FILTER
To separate insoluble substance from a liquid by pouring mixture through filter paper.

FILTRATE
Liquid that passes through a filter leaving insoluble substance behind.

FLAMMABLE
Describes substance which easily bursts into flame.

FLASH POINT
Minimum temperature at which vapor of volatile liquid ignites in the presence of a flame.

FUEL
Substance burned to release heat energy to be used as power, e.g. coal, gas.

GAMMA RADIATION
Emission of short wavelength, highly penetrative gamma rays from radioactive elements.

GAS
State of matter, with no definite volume, whose molecules move freely to fill any available space.

HALOGEN
Group of nonmetals including fluorine and chlorine.

HYDROCARBON
Organic compound containing carbon and hydrogen.

HYDROLYSIS
Reaction in which water decomposes a substance.

HYGROSCOPIC
Describes substances which tend to absorb water from the air, e.g. sodium chloride.

IMMISCIBLE
Describes liquids that do not mix, e.g. water and oil.

INERT GAS
Gas which does not take part in chemical reactions, e.g. helium, argon.

INORGANIC CHEMISTRY
Branch of chemistry concerned with substances of mineral origin.

INSOLUBLE
Describes substance that cannot be dissolved in a particular liquid.

ION
Atom or molecule carrying an electric charge. Formed by atom losing (produces positive ion) or gaining (produces negative ion) one or more electrons.

IONIC BOND
Chemical bond formed between ions, e.g. between sodium ion and chloride ion.

IONIZATION
Process of ion formation.

ISOMERS
Compounds with same empirical formulas but with different molecular structures.

ISOTOPES
Atoms of the same element with different atomic masses, e.g. carbon-12 and carbon-13.

LIQUID State of matter with definite volume, but which takes the shape of its container.

METAL
An element which forms positive ions during chemical reactions, is a conductor of electricity, and is lustrous, ductile, and malleable.

MISCIBLE
Describes liquids that readily mix, e.g. water and ethanol.

MIXTURE
Two or more substances, put together but not chemically joined, and which can be separated without chemical action.

MOLARITY
Number of moles of a solute in one liter of solution.

MOLE
Standard for measuring quantity of a substance. Equals the amount of a substance that contains the same number of atoms or molecules as 12 grams of carbon-12.

MOLECULE
Two or more atoms joined by covalent bonds.

MONOMER
Compound consisting of single molecules which may join with other compounds to form polymers.

NEUTRALIZATION
Reaction between an acid and an alkaline, or base, to form a salt and water.

NEUTRON
Subatomic particle with same mass as proton but no electric charge.

NOBLE METALS
Metals that resist corrosion by water and acid, e.g. gold, silver, platinum.

ORGANIC CHEMISTRY
Branch of chemistry concerned with carbon and its compounds.

ORGANIC COMPOUNDS
Compounds of carbon.

OXIDATION
Removal of electrons from an atom, originally defined as the addition of oxygen to an element or compound. Oxidation is the reverse of reduction.

OXIDIZING AGENT
Substance which oxidizes other elements or compounds.

PERIODIC TABLE
Arrangement of elements, in periods and groups in order of increasing atomic number.

ph
Measure of how acid or alkaline a solution is on a scale of 1 (very acid) through 7 (neutral) to 14 (very alkaline).

PHYSICAL CHEMISTRY
Branch of chemistry which uses physics to study the physical changes occurring during chemical reactions.

PLASTIC
Substance produced synthetically by polymerization of organic compounds.

POLYMER
Compound formed by the joining of many monomers, with high relative molecular mass, produced by polymerization.

POLYMERIZATION
Process in which many molecules combine to form larger molecules.

PRECIPITATE
Solid substance which separates from a solution during a chemical reaction.

PRODUCT
New substance produced as the result of a chemical reaction.

PROTON
Subatomic particle with positive charge.

RADIOACTIVE ELEMENT
Element whose nuclei emit subatomic particles (radiation) and which, as a consequence, break up into simpler elements or more stable isotopes of the same element.

REACTANT
Substance that partakes in chemical reaction.

REACTION
Process whereby substances (reactants) are chemically changed to form new substances (products).

REDOX REACTION
Mutual oxidation and reduction, so that when substance X oxidizes substance Y, substance Y reduces substance X.

REDUCING AGENT
Substance that reduces other compounds by being itself oxidized.

REDUCTION
Addition of electrons to an atom; originally defined as reactions involving the removal of oxygen from a compound. Reduction is the reverse of oxidation.

RELATIVE ATOMIC MASS
Measurement of mass of one atom of an element, equals ratio of mass of one atom of a particular element to one atomic mass unit.

RELATIVE MOLECULAR MASS
Measurement of the average mass per molecule of a substance. Calculated by adding together the relative atomic masses of its constituent atoms.

SALT
A compound formed as the result of a reaction in which a metal replaces the hydrogen of an acid, e.g. calcium chloride.

SATURATED SOLUTION
Solution in which no further solute can be dissolved.

SOLID
State of matter with a definite volume and definite shape.

SOLUBLE
Describes property of a substance that can be dissolved in a particular liquid.

SOLUTE
Substance that dissolves in a particular liquid.

SOLUTION
Result of dissolved a solute in a solvent, the tow cannot be separated by filtration or other mechanical methods.

SOLVENT
Liquid in which a particular solute can dissolve.

SUBATOMIC PARTICLE
Small particles that make up atoms.

SUBLIMATION
Direct change of state from a solid to a vapor by heating.

SUBSTANCE
Element or compound with recognizable properties that do not vary, e.g. sugar, tin.

SUSPENSION
A mixture of small insoluble particles in a liquid which can be removed by filtration, e.g. clay particles in water.

THERMOCHEMISTRY
Study of changes in heat energy during a chemical reaction.

THERMOLABILE
Describes substances that decompose when heated.

THERMOSTABLE
Describes substances that are stable when heated.

VALENCE ELECTRON
Electron in outer shell of atom that takes part in bond formation.

VALENCY
Measure of ability of an atom to form bonds with other atoms.

VAN DER WAALS' BOND
A type of weak bond that holds molecules together.