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A & P Test 1 materials

Polar covalent bond

A bond in which electrons are shared unequally.

Ionic bond

A bond in which electrons are completely lost or gained by the atoms involved.

Nonpolar covalent bond

A bond in which electrons are shared equally.

Hydrogen bond

A type of bond important in tying different parts of the same molecule together into a three-dimensional structure.


Electrically charged particle due to loss of an electron.


Neutral subatomic particle.


Smallest particle of an element that retains its properties; composed of protons, neutrons, and electrons.


Smallest particle of a compound that still retains its properties.


A substance that releases hydrogen ions when in solution (compare with Base); a proton donor.


State of abnormally high hydrogen ion concentration in the extracellular fluid.

Activation energy

The amount of energy required to push a reactant to the level necessary for action.

Active site

Region on the surface of a functional (globular) protein where it binds and interacts chemically with other molecules of complementary shape and charge.

Adenine (A)

One of the two major purines found in both RNA and DNA; also found in various free nucleotides of importance to the body, such as ATP.

Adenosine triphosphate (ATP)

Organic molecule that stores and releases chemical energy for use in body cells.


State of abnormally low hydrogen ion concentration in the extracellular fluid.


The most common type of secondary structure of the amino acid chain in proteins; resembles the coils of a telephone cord.

Amino acid

Organic compound containing nitrogen, carbon, hydrogen, and oxygen; building block of protein.

Ammonia (NH3)

Common waste product of protein breakdown in the body; a colorless volatile gas, very soluble in water and capable of forming a weak base; a proton acceptor.


An ion carrying one or more negative charges and therefore attracted to a positive pole.


The protein portion of an enzyme.

Atomic number

The number of protons in an atom.

Atomic symbol

The one- or two-letter symbol used to indicate an element; usually the first letter(s) of the element's name.

Atomic weight

The average of the mass numbers of all the isotopes of an element.

ATP (sdenosine triphosphate)

Organic molecule that stores and releases chemical energy for use in body cells.

Avogadro's number

The number of molecules in one mole of any substance, 6.02 x 1023.


A substance capable of binding with hydrogen ions; a proton acceptor.


Chemical substance or system that minimizes changes in pH by releasing or binding hydrogen ions.


Organic compound composed of carbon, hydrogen, and oxygen; includes starches, sugars, cellulose.


Substance that increases the rate of a chemical reaction without itself becoming chemically changed or part of the product.


An ion with a positive charge.


A fibrous carbohydrate that is the main structural component of plant tissues.

Chemical bond

An energy relationship holding atoms together; involves the interaction of electrons.

Chemical energy

Energy stored in the bonds of chemical substances.

Chemical equilibrium

A state of apparent repose created by two reactions proceeding in opposite directions at equal speed.

Chemical reaction

Process in which molecules are formed, changed, or broken down.


Nonprotein substance associated with and activating an enzyme, typically a vitamin.


Metal ion or organic molecule that is required for enzyme activity.


(1) A mixture in which the solute particles (usually proteins) do not settle out readily. (2) Substance in the thyroid gland containing thyroglobulin protein.

Combination (synthesis) reaction

Chemical reaction in which larger, more complex atoms or molecules are formed from simpler ones.

Complementary base

Refers to how a given nitrogenous base of DNA or RNA bonds to another nitrogenous base. For example, adenine (A) is the complementary base of thymine (T). The result is base pairing.


Substance composed of two or more different elements, the atoms of which are chemically united.

Covalent bond

Chemical bond created by electron sharing between atoms.

Cytosine (C)

Nitrogen-containing base that is part of a nucleotide structure.

Decomposition reaction

Chemical reaction in which a molecule is broken down into smaller molecules or its constituent atoms.

Dehydration synthesis

Process by which a large molecule is synthesized by removing water and covalently bonding smaller molecules together.


A combination of two amino acids united by means of a peptide bond.

Dipole (polar molecule)

Nonsymmetrical molecules that contain electrically unbalanced atoms.


Literally, double sugar; e.g., sucrose, lactose.

Displacement (exchange) reaction

Chemical reaction in which bonds are both made and broken; atoms become combined with different atoms.


A nucleic acid found in all living cells; it carries the organism's hereditary information.

Double helix

The secondary structure assumed by two strands of DNA, held together throughout their length by hydrogen bonds between bases on opposite strands.

Electrical energy

Energy formed by the movement of charged particles across cell membranes.


Negatively charged subatomic particle; orbits the atom's nucleus.

electron shells (energy level)

Regions of space that consecutively surround the nucleus of an atom.


One of a limited number of unique varieties of matter that composes substances of all kinds; e.g., carbon, hydrogen, oxygen.

Endergonic reaction

Chemical reaction that absorbs energy, e.g., an anabolic reaction.


The capacity to do work; may be stored (potential energy) or in action (kinetic energy).


A protein that acts as a biological catalyst to speed up a chemical reaction.

Exchange (displacement) reaction

Chemical reaction in which bonds are both made and broken; atoms become combined with different atoms.

Exergonic reaction

Chemical reaction that releases energy, e.g., a catabolic or oxidative reaction.

Fatty acids

Linear chains of carbon and hydrogen atoms (hydrocarbon chains) with an organic acid group at one end. A constituent of fat.




Main carbohydrate stored in animal cells; a polysaccharide.

Hydrogen bond

Weak bond in which a hydrogen atom forms a bridge between two electron-hungry atoms. An important intramolecular bond.

Hydrogen ion

A hydrogen atom minus its electron and therefore carrying a positive charge (i.e., a proton).


Process in which water is used to split a substance into smaller particles.

Hydroxyl ion (OH)

An ion liberated when a hydroxide (a common inorganic base) is dissolved in water.

Inorganic compound

Chemical substances that do not contain carbon, including water, salts, and many acids and bases.


Atom with a positive or negative electric charge.

Ionic bond

Chemical bond formed by electron transfer between atoms.


One of two or more substances that has the same molecular formula but with its atoms arranged differently.


Different atomic forms of the same element, vary only in the number of neutrons they contain; the heavier species tend to be radioactive.


Excess levels of ketone bodies in blood. Called ketoacidosis if blood pH is low.

Kinetic energy

The energy of motion or movement, e.g., the constant movement of atoms, or the push given to a swinging door that sets it into motion.


Organic compound formed of carbon, hydrogen, and oxygen; examples are fats and cholesterol.


Large, complex molecules containing from 100 to over 10,000 subunits.

Mass number

Sum of the number of protons and neutrons in the nucleus of an atom.

Mechanical energy

The energy directly involved in moving matter; e.g., in bicycle riding, the legs provide the mechanical energy that moves the pedals.


A way to express the concentration of a solution; moles per liter of solution.


A mole of any element or compound is equal to its atomic weight or its molecular weight (sum of atomic weights) measured in grams.


Particle consisting of two or more atoms joined together by chemical bonds.

Neutral fats

Consist of fatty acid chains and glycerol; also called triglycerides or triacylglycerols. Commonly known as oils when liquid.

Neutralization reaction

Displacement reaction in which mixing an acid and a base forms water and a salt.


Uncharged subatomic particle; found in the atomic nucleus.

Nonpolar molecules

Electrically balanced molecules.

Nucleic acid

Class of organic molecules that includes DNA and RNA.


Building block of nucleic acids; consists of a sugar, a nitrogen-containing base, and a phosphate group.

Octet rule (rule of eights)

The tendency of atoms to interact in such a way that they have eight electrons in their valence shell.

Organic compound

Any compound composed of atoms (some of which are carbon) held together by covalent (shared electron) bonds.


Process of substances combining with oxygen or the removal of hydrogen.

Oxidation-reduction (redox) reaction

Process of substances combining with oxygen or the removal of hydrogen.

Peptide bond

Bond joining the amine group of one amino acid to the acid carboxyl group of a second amino acid with the loss of a water molecule.

pH unit

The measure of the relative acidity or alkalinity of a solution.


Modified lipid, contains phosphorus.

Polar molecules

Nonsymmetrical molecules that contain electrically unbalanced atoms.


A substance of high molecular weight with long, chainlike molecules consisting of many similar (repeated) units.


A chain of amino acids.


Literally, many sugars, a polymer of linked monosaccharides; e.g., starch, glycogen.

Potential energy

Stored or inactive energy.


Complex substance containing carbon, oxygen, hydrogen, and nitrogen; composes 10-30% of cell mass.


Subatomic particle that bears a positive charge; located in the atomic nucleus.

Proton acceptor

A substance that takes up hydrogen ions in detectable amounts. Commonly referred to as a base.

Proton donor

A substance that releases hydrogen ions in detectable amounts; an acid.


The process of spontaneous decay seen in some of the heavier isotopes, during which particles or energy is emitted from the atomic nucleus; results in the atom becoming more stable.


Isotope that exhibits radioactive behavior.


A substance taking part in a chemical reaction.


Chemical reaction in which electrons and energy are gained by a molecule (often accompanied by gain of hydrogen ions) or oxygen is lost.


Nucleic acid that contains ribose and the bases A, G, C, and U. Carries out DNA's instructions for protein synthesis.

Sol-gel transformation

Reversible change of a colloid from a fluid (sol) to a more solid (gel) state.


The substance that is dissolved in a solution.


Group of chemical substances including certain hormones and cholesterol; they are fat soluble and contain little oxygen.

Structural (fibrous) proteins

Consist of extended, strandlike polypeptide chains forming a strong, ropelike structure that is linear, insoluble in water, and very stable; e.g., collagen.


A reactant on which an enzyme acts to cause a chemical action to proceed.


Heterogeneous mixtures with large, often visible solutes that tend to settle out.

Synthesis (combination) reaction

A chemical reaction in which larger, more complex atoms or molecules are formed from simpler ones.

Thymine (T)

Single-ring base (a pyrimidine) in DNA.


Fats and oils composed of fatty acids and glycerol; are the body's most concentrated source of energy fuel; also known as neutral fats.

Uracil (U)

A smaller, single-ring base (a pyrimidine) found in RNA.

Valance shell

Outermost electron shell (energy level) of an atom that contains electrons

Hydrogen bonds are comparatively strong bonds.


The fact that no chemical bonding occurs between the components of a mixture is the chief difference between mixtures and compounds.


Alpha particles, although relatively weak energy particles, are second only to smoking as a cause of lung cancer.


No chemical bonding occurs between the components of a mixture.


All organic compounds contain carbon.


A dipeptide can be broken into two amino acids by dehydration synthesis.


The pH of body fluids must remain fairly constant for the body to maintain homeostasis.


Mixtures are combinations of elements or compounds that are physically blended together but are not bound by chemical bonds.


Buffers resist abrupt and large changes in the pH of the body by releasing or binding ions.


Which of the following elements is necessary for proper conduction of nervous impulses?
A) Na B) Fe C) I D) P


59) Choose the statement that is false or incorrect.
A) In chemical reactions, breaking old bonds requires energy and forming new bonds releases
B) Exergonic reactions release more energy than they absorb.
C) A key feature of the body's metabolism is the almost exclusive use of exergonic reactions by
the body.
D) Endergonic reactions absorb more energy than they release.


In general, the lipids that we refer to as oils have ________.
A) a high degree of saturated bonds
B) a high water content
C) a high degree of unsaturated bonds
D) long fatty acid chains


The genetic information is coded in DNA by the ________.
A) sequence of the nucleotides
B) three-dimensional structure of the double helix
C) regular alteration of sugar and phosphate molecules
D) arrangement of the histones


Which of the following is not true of proteins?
A) They appear to be the molecular carriers of the coded hereditary information.
B) Their function depends on the three-dimensional shape.
C) Some types are called enzymes.
D) They may be denatured or coagulated by heat or acidity.


The single most abundant protein in the body is ________. A) collagen
B) glucose
D) hemoglobin


Carbohydrates are stored in the liver and muscles in the form of ________.
A) triglycerides
B) glycogen
C) cholesterol
D) glucose


Which of the following describes coenzymes?
A) organic molecules derived from vitamins
B) enzymes that work together
C) metal ions
D) two enzymes that perform the same function


Which of the following is not a role of molecular chaperonins?
A) aid the desired folding and association process of polypeptides
B) promote the breakdown of damaged or denatured proteins
C) prevent accidental, premature, or incorrect folding of polypeptide chains
D) act as a biological catalyst
E) help to translocate proteins and certain metal ions across cell membranes


A chemical reaction in which bonds are broken is usually associated with ________.
A) the consumption of energy
B) the release of energy
C) a synthesis
D) forming a larger molecule


Salts are always ________.
A) double covalent compounds B) single covalent compounds
C) ionic compounds D) hydrogen bonded


The numbers listed represent the number of electrons in the first, second, and third energy levels, respectively. On this basis, which of the following is an unstable or reactive atom?
A) 2
B) 2, 8, 1
C) 2, 8
D) 2, 8, 8


A solution that has a pH of 2 could best be described as being ________.
A) basic
B) slightly acidic
C) neutral
D) acidic


Which of the following is the major positive ion outside cells?
A) potassium
B) hydrogen
C) nitrogen
D) sodium


Which of the following would be regarded as an organic molecule?
A) CH4
C) H2O
D) NaCl


What is a chain of 25 amino acids called?
A) protein
B) polypeptide
C) starch
D) nucleotide


Which of the following constitutes a long chain of simple sugars?
A) polysaccharide
B) protein
C) monosaccharide
D) nucleic acid


What level of protein synthesis is represented by the coiling of the protein chain backbone into an alpha helix?
A) primary structure
B) quaternary structure
C) tertiary structure
D) secondary structure


Carbohydrates and proteins are built up from their basic building blocks by the ________.
A) addition of a water molecule between each two units
B) removal of a nitrogen atom between each two units
C) removal of a water molecule between each two units
D) addition of a carbon atom between each two units


Which statement about enzymes is false?
A) Enzymes are composed mostly of protein.
B) Enzymes may be damaged by high temperature.
C) Enzymes raise the activation energy needed to start a reaction.
D) Enzymes are organic catalysts.


Which of the following statements is false?
A) Larger particles move faster than smaller ones and thus collide more frequently and more
B) Chemical reactions progress at a faster rate when the reacting particles are present in higher
C) Catalysts increase the rate of chemical reactions.
D) Chemical reactions proceed more quickly at higher temperatures.


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