Kapitel 2 Flashcards
(175 cards)
1
Q
Positively charged ion generated by the removal of an electron from a hydrogen atom; often used to refer to a proton (H+) in aqueous solution. Its presence is the basis of acidity.
A
hydrogen ion
2
Q
amino group
A
Functional group (–NH2) derived from ammonia. Can accept a proton and carry a positive charge in aqueous solution.
3
Q
One of two or more substances that contains the same atoms and has the same molecular formula (such as C6H12O6) as the other - but differs from the other in the spatial arrangement of these atoms. Optical isomers are mirror images of each other.
A
isomer (stereoisomer)
4
Q
aldehyde
A
Reactive organic compound that contains the HC=O group - for example - glyceraldehyde.
5
Q
hydrogen bond
A
A weak noncovalent interaction between a positively charged hydrogen atom in one molecule and a negatively charged atom - such as nitrogen or oxygen - in another; these interactions are key to the structure and properties of water.
6
Q
nucleic acid
A
Macromolecule that consists of a chain of nucleotides joined together by phosphodiester bonds; RNA or DNA.
7
Q
hydrolysis
A
Chemical reaction that involves cleavage of a covalent bond with the accompanying consumption of water (its –H being added to one product of the cleavage and its –OH to the other); the reverse of condensation.
8
Q
In chemistry - describes a molecule or bond in which electrons are distributed unevenly.
A
polar
9
Q
The strength of the chemical linkage between two atoms - measured by the energy in kilocalories needed to break it.
A
bond energy
10
Q
Chemical group consisting of a hydrogen atom linked to an oxygen - as in an alcohol.
A
hydroxyl (–OH)
11
Q
Avogadro’s number
A
The number of molecules in a mole - the quantity of a substance equal to its molecular weight in grams; approximately 6 × 1023.
12
Q
Molecule made of a nitrogen-containing ring compound attached to a sugar - either ribose (in RNA) or deoxyribose (in DNA).
A
nucleoside
13
Q
condensation reaction
A
Chemical reaction in which a covalent bond is formed between two molecules as water is expelled; used to build polymers - such as proteins - polysaccharides - and nucleic acids.
14
Q
phosphodiester bond
A
Strong covalent bond that forms the backbone of DNA and RNA molecules; links the 3′ carbon of one sugar to the 5′ carbon of another.
15
Q
Chemical reaction that involves cleavage of a covalent bond with the accompanying consumption of water (its –H being added to one product of the cleavage and its –OH to the other); the reverse of condensation.
A
hydrolysis
16
Q
polynucleotide
A
A molecular chain of nucleotides chemically linked by a series of phosphodiester bonds. A strand of RNA or DNA.
17
Q
ion
A
An atom carrying an electrical charge - either positive or negative.
18
Q
methyl (–CH3) group
A
Hydrophobic chemical group derived from methane (CH4).
19
Q
The amount of a substance - in grams - that is equal to its molecular weight; this quantity will contain 6 × 1023 molecules of the substance.
A
mole
20
Q
nucleotide
A
Basic building block of the nucleic acids - DNA and RNA; includes a nucleoside with a series of one or more phosphate groups linked to its sugar.
21
Q
atomic mass
A
The mass of an atom expressed in daltons - the atomic mass unit that closely approximates the mass of a hydrogen atom.
22
Q
lipid bilayer
A
Thin pair of closely juxtaposed sheets - composed mainly of phospholipid molecules - that forms the structural basis for all cell membranes.
23
Q
The linear order of monomers in a large molecule - for example amino acids in a protein or nucleotides in DNA; encodes information that specifies a macromolecule’s precise biological function.
A
sequence
24
Q
Hydrophobic chemical group derived from methane (CH4).
A
methyl (–CH3) group
25
organic molecule
Chemical compound that contains carbon and hydrogen.
26
solute
Any substance that is dissolved in a liquid. The liquid is called the solvent.
27
Substance that cannot be broken down to any other chemical form; composed of a single type of atom.
element
28
Molecule containing an amino group (–NH2).
amine
29
pH scale
Concentration of hydrogen ions in a solution - expressed as a logarithm. Thus - an acidic solution with pH 3 will contain 10–3 M hydrogen ions.
30
monomer
Small molecule that can be linked to others of a similar type to form a larger molecule (polymer).
31
ionic bond
Interaction formed when one atom donates electrons to another; this transfer of electrons causes both atoms to become electrically charged.
32
The number of electrons an atom must gain or lose (either by electron sharing or electron transfer) to achieve a filled outer shell. For example - Na must lose one electron - and Cl must gain one electron. This number is also equal to the number of single bonds that the atom can form.
valence
33
Carbon atom linked to an oxygen atom by a double bond.
carbonyl group
34
hydrophobic interaction
Type of noncovalent bond that forces together the hydrophobic portions of dissolved molecules to minimize their disruption of the hydrogen-bonded network of water; helps push together membrane phospholipids and fold proteins into a compact - globular shape.
35
carboxyl group
Carbon atom linked to an oxygen atom by a double bond and to a hydroxyl group (–COOH). In aqueous solution - acts as a weak acid.
36
Linear or branched polymer composed of sugars. Examples are glycogen - hyaluronic acid - and cellulose.
polysaccharide
37
polysaccharide
Linear or branched polymer composed of sugars. Examples are glycogen - hyaluronic acid - and cellulose.
38
Unit of molecular mass. Defined as one-twelfth the mass of an atom of carbon 12 (1.66 × 10-24 g); approximately equal to the mass of a hydrogen atom.
dalton
39
See DNA
deoxyribonucleic acid
40
kilocalorie (kcal)
Unit of heat equal to 1000 calories. Often used to express the energy content of food or molecules: bond strengths - for example - are measured in kcal/mole. An alternative unit in wide use is the kilojoule.
41
amine
Molecule containing an amino group (–NH2).
42
Small molecule that can be linked to others of a similar type to form a larger molecule (polymer).
monomer
43
Interaction formed when one atom donates electrons to another; this transfer of electrons causes both atoms to become electrically charged.
ionic bond
44
kilojoule (kJ)
Standard unit of energy equal to 0.239 kilocalories.
45
Any substance that is dissolved in a liquid. The liquid is called the solvent.
solute
46
Nonpolar - uncharged molecule or part of a molecule that forms few or no hydrogen bonds with water molecules and therefore does not dissolve; literally - “water fearing.”
hydrophobic
47
Molecule or part of a molecule that readily forms hydrogen bonds with water - allowing it to dissolve; literally - “water loving.”
hydrophilic
48
anion
Negatively charged ion - such as Cl- or CH3COO-.
49
calorie
Unit of heat. Equal to the amount of heat needed to raise the temperature of 1 gram of water by 1°C.
50
Chemical association that does not involve the sharing of electrons; singly are relatively weak - but can sum together to produce strong - highly specific interactions between molecules. Examples are hydrogen bonds and van der Waals attractions.
noncovalent bond
51
covalent bond
Stable chemical link between two atoms produced by sharing one or more pairs of electrons.
52
hydroxyl (–OH)
Chemical group consisting of a hydrogen atom linked to an oxygen - as in an alcohol.
53
conformation
Precise - three-dimensional shape of a protein or other macromolecule - based on the spatial location of its atoms in relation to one another.
54
carbohydrate
General term for sugars and related compounds with the general formula (CH2O)n.
55
bond energy
The strength of the chemical linkage between two atoms - measured by the energy in kilocalories needed to break it.
56
Small organic molecule containing both an amino group and a carboxyl group; it serves as the building block of proteins.
amino acid
57
Molecule that serves as the principal carrier of energy in cells; this nucleoside triphosphate is composed of adenine - ribose - and three phosphate groups.
ATP (adenosine 5′-triphosphate)
58
hydrophobic
Nonpolar - uncharged molecule or part of a molecule that forms few or no hydrogen bonds with water molecules and therefore does not dissolve; literally - “water fearing.”
59
trans
Beyond - or on the other side.
60
isotope
A variant of an element that has the same number of protons but a different atomic weight. Some are radioactive.
61
cis
On the same side as.
62
dalton
Unit of molecular mass. Defined as one-twelfth the mass of an atom of carbon 12 (1.66 × 10-24 g); approximately equal to the mass of a hydrogen atom.
63
A weak noncovalent interaction between a positively charged hydrogen atom in one molecule and a negatively charged atom - such as nitrogen or oxygen - in another; these interactions are key to the structure and properties of water.
hydrogen bond
64
A double-ringed - nitrogen-containing compound found in DNA and RNA. Examples are adenine and guanine.
purine
65
fatty acid
Molecule that consists of a carboxylic acid attached to a long hydrocarbon chain. Used as a major source of energy during metabolism and as a starting point for the synthesis of phospholipids.
66
Molecule that consists of a carboxylic acid attached to a long hydrocarbon chain. Used as a major source of energy during metabolism and as a starting point for the synthesis of phospholipids.
fatty acid
67
Mixture of weak acids and bases that maintains the pH of a solution by releasing and taking up protons.
buffer
68
Thin pair of closely juxtaposed sheets - composed mainly of phospholipid molecules - that forms the structural basis for all cell membranes.
lipid bilayer
69
Prefix that denotes a short polymer (oligomer). May be made of amino acids (oligopeptide) - sugars (oligosaccharide) - or nucleotides (oligonucleotide).
oligo-
70
The branch of chemistry concerned with compounds made of carbon. Includes essentially all of the molecules from which living cells are made - apart from water and metal ions such as Na+.
organic chemistry
71
molecule
Group of atoms joined together by covalent bonds.
72
cation
Positively charged ion - such as Na+ or CH3NH3+.
73
hydrogen ion
Positively charged ion generated by the removal of an electron from a hydrogen atom; often used to refer to a proton (H+) in aqueous solution. Its presence is the basis of acidity.
74
Basic building block of the nucleic acids - DNA and RNA; includes a nucleoside with a series of one or more phosphate groups linked to its sugar.
nucleotide
75
Unit of heat equal to 1000 calories. Often used to express the energy content of food or molecules: bond strengths - for example - are measured in kcal/mole. An alternative unit in wide use is the kilojoule.
kilocalorie (kcal)
76
An exchange of electrons that holds two atoms together. Types found in living cells include ionic bonds - covalent bonds - and hydrogen bonds.
chemical bond
77
Reactive organic compound that contains the HC=O group - for example - glyceraldehyde.
aldehyde
78
K+
Potassium ion—the most abundant positively charged ion in living cells.
79
oligo-
Prefix that denotes a short polymer (oligomer). May be made of amino acids (oligopeptide) - sugars (oligosaccharide) - or nucleotides (oligonucleotide).
80
Concentration of hydrogen ions in a solution - expressed as a logarithm. Thus - an acidic solution with pH 3 will contain 10–3 M hydrogen ions.
pH scale
81
A substance made of carbon - hydrogen - and oxygen with the general formula (CH2O)n. A carbohydrate or saccharide. The “sugar” of everyday use is sucrose - a sweet-tasting disaccharide made of glucose and fructose.
sugar
82
mole
The amount of a substance - in grams - that is equal to its molecular weight; this quantity will contain 6 × 1023 molecules of the substance.
83
double bond
Chemical linkage formed when two atoms share four electrons.
84
van der Waals attraction
Weak noncovalent interaction - due to fluctuating electrical charges - that comes into play between two atoms within a short distance of each other.
85
sequence
The linear order of monomers in a large molecule - for example amino acids in a protein or nucleotides in DNA; encodes information that specifies a macromolecule’s precise biological function.
86
Type of noncovalent bond that forces together the hydrophobic portions of dissolved molecules to minimize their disruption of the hydrogen-bonded network of water; helps push together membrane phospholipids and fold proteins into a compact - globular shape.
hydrophobic interaction
87
Not composed of carbon and hydrogen.
inorganic
88
isomer (stereoisomer)
One of two or more substances that contains the same atoms and has the same molecular formula (such as C6H12O6) as the other - but differs from the other in the spatial arrangement of these atoms. Optical isomers are mirror images of each other.
89
A monomer that forms part of a larger molecule - such as an amino acid residue in a protein or a nucleotide residue in a nucleic acid. Can also refer to a complete molecule that forms part of a larger molecule. Many proteins - for example - are composed of multiple polypeptide chains - each of which is called a protein subunit.
subunit
90
amide
Molecule containing the functional group –CONH2.
91
noncovalent bond
Chemical association that does not involve the sharing of electrons; singly are relatively weak - but can sum together to produce strong - highly specific interactions between molecules. Examples are hydrogen bonds and van der Waals attractions.
92
hydrophilic
Molecule or part of a molecule that readily forms hydrogen bonds with water - allowing it to dissolve; literally - “water loving.”
93
atom
The smallest particle of an element that still retains its distinctive chemical properties; consists of a positively charged nucleus surrounded by a cloud of negatively charged electrons.
94
glycolipid
Membrane lipid molecule that has a short carbohydrate chain attached to its hydrophilic head.
95
A variant of an element that has the same number of protons but a different atomic weight. Some are radioactive.
isotope
96
The number of molecules in a mole - the quantity of a substance equal to its molecular weight in grams; approximately 6 × 1023.
Avogadro’s number
97
Molecule containing the functional group –CONH2.
amide
98
element
Substance that cannot be broken down to any other chemical form; composed of a single type of atom.
99
Beyond - or on the other side.
trans
100
Stable chemical link between two atoms produced by sharing one or more pairs of electrons.
covalent bond
101
lipid
Organic molecule that is insoluble in water but dissolves readily in nonpolar organic solvents; typically contains long hydrocarbon chains or multiple rings. One class - the phospholipids - forms the structural basis of biological membranes.
102
Standard unit of energy equal to 0.239 kilocalories.
kilojoule (kJ)
103
Describes a molecule that lacks a local accumulation of positive or negative charge; generally insoluble in water.
nonpolar
104
macromolecule
Polymer built from covalently linked subunits; includes proteins - nucleic acids - and polysaccharides with a molecular mass greater than a few thousand daltons.
105
Negatively charged ion - such as Cl- or CH3COO-.
anion
106
Na+
Sodium ion—a positively charged ion that is a major constituent of living cells.
107
Sum of the atomic weights of the atoms in a molecule; as a ratio of molecular masses - it is a number without units.
molecular weight
108
nucleoside
Molecule made of a nitrogen-containing ring compound attached to a sugar - either ribose (in RNA) or deoxyribose (in DNA).
109
polymer
Long molecule made by covalently linking multiple identical or similar subunits (monomers).
110
subunit
A monomer that forms part of a larger molecule - such as an amino acid residue in a protein or a nucleotide residue in a nucleic acid. Can also refer to a complete molecule that forms part of a larger molecule. Many proteins - for example - are composed of multiple polypeptide chains - each of which is called a protein subunit.
111
Macromolecule that consists of a chain of nucleotides joined together by phosphodiester bonds; RNA or DNA.
nucleic acid
112
amino acid
Small organic molecule containing both an amino group and a carboxyl group; it serves as the building block of proteins.
113
A nitrogen-containing - six-membered ring compound found in DNA and RNA. Examples are thymine - cytosine - and uracil.
pyrimidine
114
Membrane lipid molecule that has a short carbohydrate chain attached to its hydrophilic head.
glycolipid
115
Polymer built from covalently linked subunits; includes proteins - nucleic acids - and polysaccharides with a molecular mass greater than a few thousand daltons.
macromolecule
116
valence
The number of electrons an atom must gain or lose (either by electron sharing or electron transfer) to achieve a filled outer shell. For example - Na must lose one electron - and Cl must gain one electron. This number is also equal to the number of single bonds that the atom can form.
117
Carbon atom linked to an oxygen atom by a double bond and to a hydroxyl group (–COOH). In aqueous solution - acts as a weak acid.
carboxyl group
118
purine
A double-ringed - nitrogen-containing compound found in DNA and RNA. Examples are adenine and guanine.
119
acyl group
Functional group derived from a carboxylic acid.
120
Functional group derived from a carboxylic acid.
acyl group
121
organic chemistry
The branch of chemistry concerned with compounds made of carbon. Includes essentially all of the molecules from which living cells are made - apart from water and metal ions such as Na+.
122
Average distance between two interacting atoms in a molecule - usually those linked covalently.
bond length
123
Molecule that accepts a proton when dissolved in water; also used to refer to the nitrogen-containing purines or pyrimidines in DNA and RNA.
base
124
bond length
Average distance between two interacting atoms in a molecule - usually those linked covalently.
125
hydronium ion (H3O+)
The form taken by a proton (H+)) in aqueous solution.
126
Potassium ion—the most abundant positively charged ion in living cells.
K+
127
Sodium ion—a positively charged ion that is a major constituent of living cells.
Na+
128
polar
In chemistry - describes a molecule or bond in which electrons are distributed unevenly.
129
Functional group (–NH2) derived from ammonia. Can accept a proton and carry a positive charge in aqueous solution.
amino group
130
ATP (adenosine 5′-triphosphate)
Molecule that serves as the principal carrier of energy in cells; this nucleoside triphosphate is composed of adenine - ribose - and three phosphate groups.
131
Strong covalent bond that forms the backbone of DNA and RNA molecules; links the 3′ carbon of one sugar to the 5′ carbon of another.
phosphodiester bond
132
chemical group
Combination of atoms - such as a hydroxyl group (–OH) or an amino group (–NH2) - with distinct chemical and physical properties that influences the behavior of the molecule in which it resides.
133
The smallest particle of an element that still retains its distinctive chemical properties; consists of a positively charged nucleus surrounded by a cloud of negatively charged electrons.
atom
134
Combination of atoms - such as a hydroxyl group (–OH) or an amino group (–NH2) - with distinct chemical and physical properties that influences the behavior of the molecule in which it resides.
chemical group
135
alkyl group
Functional group consisting solely of single-bonded carbon and hydrogen atoms - such as methyl (–CH3) or ethyl (–CH2CH3) groups.
136
triacylglycerol
Compound made of three fatty acid tails covalently attached to glycerol. A storage form of fat - the main constituent of fat droplets in animal tissues (in which the fatty acids are saturated) and of vegetable oil from plants (in which the fatty acids are mainly unsaturated).
137
group
See chemical group
138
Chemical compound that contains carbon and hydrogen.
organic molecule
139
inorganic
Not composed of carbon and hydrogen.
140
pyrimidine
A nitrogen-containing - six-membered ring compound found in DNA and RNA. Examples are thymine - cytosine - and uracil.
141
nonpolar
Describes a molecule that lacks a local accumulation of positive or negative charge; generally insoluble in water.
142
Group of atoms joined together by covalent bonds.
molecule
143
A molecular chain of nucleotides chemically linked by a series of phosphodiester bonds. A strand of RNA or DNA.
polynucleotide
144
Force that draws together oppositely charged atoms. Examples include ionic bonds and the attractions between molecules containing polar covalent bonds.
electrostatic attraction
145
base
Molecule that accepts a proton when dissolved in water; also used to refer to the nitrogen-containing purines or pyrimidines in DNA and RNA.
146
proton
Positively charged particle found in the nucleus of every atom; also - another name for a hydrogen ion (H+).
147
Positively charged ion - such as Na+ or CH3NH3+.
cation
148
Chemical reaction in which a covalent bond is formed between two molecules as water is expelled; used to build polymers - such as proteins - polysaccharides - and nucleic acids.
condensation reaction
149
A molecule that releases a proton when dissolved in water; this dissociation generates hydronium (H 3O+) ions - thereby lowering the pH.
acid
150
Functional group consisting solely of single-bonded carbon and hydrogen atoms - such as methyl (–CH3) or ethyl (–CH2CH3) groups.
alkyl group
151
Organic compound containing a hydroxyl group (–OH) bound to a saturated carbon atom - for example - ethanol.
alcohol
152
sugar
A substance made of carbon - hydrogen - and oxygen with the general formula (CH2O)n. A carbohydrate or saccharide. The “sugar” of everyday use is sucrose - a sweet-tasting disaccharide made of glucose and fructose.
153
Precise - three-dimensional shape of a protein or other macromolecule - based on the spatial location of its atoms in relation to one another.
conformation
154
The mass of an atom expressed in daltons - the atomic mass unit that closely approximates the mass of a hydrogen atom.
atomic mass
155
Chemical linkage formed when two atoms share four electrons.
double bond
156
buffer
Mixture of weak acids and bases that maintains the pH of a solution by releasing and taking up protons.
157
See C-terminus
carboxyl terminus
158
On the same side as.
cis
159
acid
A molecule that releases a proton when dissolved in water; this dissociation generates hydronium (H 3O+) ions - thereby lowering the pH.
160
General term for sugars and related compounds with the general formula (CH2O)n.
carbohydrate
161
carbonyl group
Carbon atom linked to an oxygen atom by a double bond.
162
alcohol
Organic compound containing a hydroxyl group (–OH) bound to a saturated carbon atom - for example - ethanol.
163
The form taken by a proton (H+)) in aqueous solution.
hydronium ion (H3O+)
164
chemical bond
An exchange of electrons that holds two atoms together. Types found in living cells include ionic bonds - covalent bonds - and hydrogen bonds.
165
electrostatic attraction
Force that draws together oppositely charged atoms. Examples include ionic bonds and the attractions between molecules containing polar covalent bonds.
166
Unit of heat. Equal to the amount of heat needed to raise the temperature of 1 gram of water by 1°C.
calorie
167
Weak noncovalent interaction - due to fluctuating electrical charges - that comes into play between two atoms within a short distance of each other.
van der Waals attraction
168
Compound made of three fatty acid tails covalently attached to glycerol. A storage form of fat - the main constituent of fat droplets in animal tissues (in which the fatty acids are saturated) and of vegetable oil from plants (in which the fatty acids are mainly unsaturated).
triacylglycerol
169
Positively charged particle found in the nucleus of every atom; also - another name for a hydrogen ion (H+).
proton
170
The weight of a molecule expressed in daltons - the atomic mass unit that closely approximates the mass of a hydrogen atom.
molecular mass
171
molecular mass
The weight of a molecule expressed in daltons - the atomic mass unit that closely approximates the mass of a hydrogen atom.
172
An atom carrying an electrical charge - either positive or negative.
ion
173
Organic molecule that is insoluble in water but dissolves readily in nonpolar organic solvents; typically contains long hydrocarbon chains or multiple rings. One class - the phospholipids - forms the structural basis of biological membranes.
lipid
174
molecular weight
Sum of the atomic weights of the atoms in a molecule; as a ratio of molecular masses - it is a number without units.
175
Long molecule made by covalently linking multiple identical or similar subunits (monomers).
polymer
