Chapter 2 Atoms, Molecules, and Life

Question 1

Acid

Answer 1

A substance that releases hydrogen ion (H+) into a solution; a solution with a pH of less than 7.

Question 2

Amino Acid

Answer 2

The individual subunit of which proteins are made, composed of a central carbon atom bonded to an amino group, a carboxyl group. a hydrogen atom, and a variable group of atoms denoted by the letter R.

Question 3

Atom

Answer 3

The smallest particle of an element that retains the properties of the element.

Question 4

Atomic Nucleus

Answer 4

The central region of an atom, consisting of protons and neutrons.

Question 5

Atomic Number

Answer 5

A number of protons in the nuclei of all atoms of a particular element.

Question 6

Base

Answer 6

(1) a substance capable of combining with and neutralizing H+ ions in a solution; a solution with a pH of more than 7; (2) in molecule genetrics, one of the nitrogen-containing, single or double ringed structures that distinguishes one nucleotide from another. In DNA, the bases are adenine, guanine, cytosine, and thymine.

Question 7

Buffer

Answer 7

A compound that minimizes changes in pH by reversibly taking up or releasing H+ ions.

Question 8

Carbohydrate

Answer 8

A compound composed of carbon, hydrogen, and oxygen, with the approximate chemical formula includes sugars and starches.

Question 9

Chemical Bond

Answer 9

The process that forms and breaks chemical bonds that hold atoms together.

Question 10

Chemical Reaction

Answer 10

The process that forms and breaks chemical onds that hold atoms together.

Question 11

Cohesion

Answer 11

The tendency of the molecules of a substance to stick together.

Question 12

Covalent Bond

Answer 12

A chemical bond between atoms in which electrons are shared.

Question 13

Dehydration Synthesis

Answer 13

A chemical reaction in which two molecules are joined by a covalent bond with the simultaneous removal of a hydrogen atom from one molecuyle and a hydroxly group from the other, forming water; the reverse of hydrolysis.

Question 14

Denature

Answer 14

To disrupt the secondary and or tertiary structure of a protein while leaving its aino acid sequence intact. Denatured proteins can no longer perform their biological functions.

Question 15

Electron

Answer 15

A subatomic particle, found in an electron shell outside the nucleus of an atom, that bears a unit of negative charge and very little mass.

Question 16

Electron Shell

Answer 16

A region within which electrons orbit that corresponds to a fixed energy level at a given distance from the atomic nucleus of an atom.

Question 17

Element

Answer 17

A substance thatt cannot be broken down, or converted, to a simpler substance by ordinary chemical means.

Question 18

Functional Group

Answer 18

One of several groups of atoms commonly found in an organic molecule, including hydrogen, hydroxyl, amino, carboxyl, and phosphate groups, that dertmine the characteristics and chemical reactivity of the molecule.

Question 19

Hydrogen Bond

Answer 19

The weak attraction between a hydrogen atom that bears a partial positive charge (due to polar covalent bonding with another atom) and another atom, normally oxygen or nitrogen, that bearts a partial negative charge; hydrogen bonds may form between atoms of a single molecule or of different molecules

Question 20

Hydrolysis

Answer 20

The chemical reaction that breaks a covalent bond by means of the addition of hydrogen to the atom on one side of the original bond and a hydroxyl to the atom on the other side; the reverse of dehydration synthesis.

Question 21

Ion

Answer 21

A charged atom or molecule; an atom or molecule that either has an excess of electrons (and hence is negatively charged) or has lost electrons (and is positively charged).

Question 22

Ionic Bond

Answer 22

A chemical bond formed by the eletrical attraction between positively and negatively charged ions.

Question 23

Isotope

Answer 23

One of several forms of a single element, the nuclei of which contain the same number of protons but different numbers of neutrons.

Question 24

Lipid

Answer 24

One of a number of organic molecules containing large nonpolar regions composed solely of carbon and hydrogen, which make lipids hydrophobic and insoluble in waterl includes oils, fats, waxes, phospholipids, and steroids.

Question 25

Molecule

Answer 25

A particle composed of one or more atoms held together by chemical bonds; the smallest particle of a compound that displays all of the properties of that compound.

Question 26

Neutron

Answer 26

A subatomic particle that is found in the nuclei of atoms, bears no charge, and has a mass approximately equal to that of a proton.

Question 27

Nonpolar Molecule

Answer 27

A molecule bound by covalent bonds in which eletrical charge is symmetrically distributed, so that no portion of the molecule is eletrically charged relative to other portions.

Question 28

Nucleic Acid

Answer 28

An organic molecule composed of nucleotide subunits; the two common types of nuclei acids are ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).

Question 29

Organic Molecule

Answer 29

A molecule that contains both carbon and hydrogen.

Question 30

pH Scale

Answer 30

A scale, with values from 0 to 14, used for the relative acidity of a solution; at pH 7 a solution is netrual, pH 0 to 7 acidic, and pH 7 to 14 is basicl each unit on the scale represents a tenfold change in H+ concentration.

Question 31

Polar Molecule

Answer 31

A molecule bound by covalent bonds in which electrical change is asymmetrically distrubuted, so that the eletrical charge differes in different portions of the molecule.

Question 32

Protein

Answer 32

A polymer of amino acids joined by peptide bonds.

Question 33

Proton

Answer 33

A subatomic particle that is found in the nuclei of atoms, bears a unit of positive charge, and has a relatively large mass, roughly equal to the mass of the neutron.

Question 34

Radioactive

Answer 34

Pertaining to an atom with an unstable nucleus that spontaneously disintegrates, with the emission of radiation.

Question 35

Solvent

Answer 35

A liquid capable of dissolving (uniformly dispersing) other substances in itself.

Question 36

Surface Tension

Answer 36

A tendency of a liquid to resist penetration by objects at its interface with the air, due to cohesion between molecules of a liquid.

Question 37

Wax

Answer 37

A lipid composed of fatty acids covalently bonded to long-chain alcohols.