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Cell and Molecular Biology > Chapter 2: Chemical Components of Cells > Flashcards

Chapter 2: Chemical Components of Cells Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

chemistry of life is based overwhelmingly on carbon compounds, the study of which is known as _________.

A

organic chemistry

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2
Q

chemistry of life depends almost exclusively on chemical reactions that take place in _______.

A

watery, or aqueous, environment

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3
Q

molecules made of many chemical subunits linked end-to- end.

A

polymers

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4
Q

The ________ of an atom, or the _________ of a molecule, is its mass relative to the mass of a hydrogen atom.

A

atomic weight or molecular weight

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5
Q

An individual carbon atom is roughly ____ in diameter.

A

0.2 nm

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6
Q

allows us to relate everyday quantities of chemicals to numbers of individual atoms or molecules.

A

Avogadro’s number

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7
Q

Living things, however, are made of only a small selection of these elements:

A
  • Carbon
  • Hydrogen
  • Nitrogen
  • Oxygen (constitute 96% of any organism’s weight)
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8
Q

there is a strict limit to the number of electrons that can be accommodated in an orbit of a given type, a so-called _____

A

electron shell

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9
Q

Matter is made of combinations of _______.

A

elements

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10
Q

substances such as hydro- gen or carbon that cannot be broken down or interconverted by chemical means.

A

elements

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11
Q

The smallest particle of an element that still retains its distinctive chemical properties is an ______.

A

atom

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12
Q

Each atom has at its center a dense, positively charged nucleus, which is surrounded at some distance by a cloud of negatively charged _____.

A

electron

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13
Q

held in orbit by electrostatic attraction to the nucleus

A

electron

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14
Q

The nucleus consists of two kinds of subatomic particles:

A

protons and neutrons

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15
Q

are positively charged

A

protons

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16
Q

are electrically neutral

A

neutrons

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17
Q

The ________ of an element is determined by the number of protons present in its atom’s nucleus.

A

atomic number

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18
Q

The electric charge carried by each proton is exactly __________ to the charge carried by a single electron.

A

equal and opposite

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19
Q

the number of ______ in an atom also equals the atomic number.

A

electrons

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20
Q

_________ have essentially the same mass as protons.

A

Neutrons

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21
Q

Neutrons contribute to the __________ of the nucleus: if there are too many or too few, the nucleus may disintegrate by radioactive decay.

A

structural stability

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22
Q

an element can exist in several physically distinguishable but chemically identical forms, called ______.

A

isotopes

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23
Q

A ________ is X grams of a substance, where X is the molecular weight of the substance.

A

mole

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24
Q

A mole will contain
______ molecules of the substance.

A

6 × 10^23

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25
Q

1 mole of carbon weighs _____.

A

12 g

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26
Q

1 mole of glucose weighs ______.

A

180 g

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27
Q

1 mole of sodium chloride weighs ____.

A

58 g

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28
Q

Multiple isotopes of almost all the elements occur ______.

A

naturally

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29
Q

The mass of an atom or a molecule is generally specified in ______.

A

daltons

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30
Q

There are about ___ naturally occurring elements, each differing from the others in the number of protons and electrons in its atoms.

A

90

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31
Q

(true or false) The Outermost Electrons Determine How Atoms Interact

A

True

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32
Q

______ are in continuous motion around the nucleus, but motions on this submicroscopic scale obey different laws from those we are familiar with in everyday life.

A

Electrons

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33
Q

there is a strict limit to the number of electrons that can be accommodated in an orbit of a given type, a so-called ________.

A

electron shell

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34
Q

The electrons closest on average to the positively charged nucleus are attracted ______ to it and occupy the inner, most tightly bound shell.

A

most strongly

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35
Q

This innermost shell can hold a maximum of ________.

A

two electrons.

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36
Q

The arrangement of electrons in an atom is most _______ when all the electrons are in the most tightly bound states that are possible for them.

A

stable

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37
Q

two types of chemical bonds:

A

ionic bonds and covalent bonds

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38
Q

is formed when electrons are donated by one atom to another

A

an ionic bond

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39
Q

is formed when two atoms share a pair of electrons

A

a covalent bond

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40
Q

a cluster of atoms held together by covalent bonds.

A

molecule

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41
Q

(true or false) The hydrogen molecule is held together by a covalent
bond.

A

true

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42
Q

The attractive and repulsive forces are precisely in balance when these nuclei are separated by a characteristic distance, called the ______.

A

bond length

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43
Q

Most covalent bonds involve the sharing of two electrons, one donated by each participating atom; these are called ________.

A

single bonds

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44
Q

In living organisms, covalent bonds are normally broken only during specific chemical reactions that are carefully controlled by highly specialized protein catalysts called _____.

A

enzymes

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45
Q

are usually formed between atoms that can attain a completely filled outer shell most easily by donating electrons to—or accepting electrons from—another atom, rather than by sharing them.

A

ionic bonds

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46
Q

Positive ions

A

cations

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47
Q

Negative ions

A

anions

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48
Q

In aqueous solution, ionic bonds are _______ weaker than the covalent bonds that hold atoms together in molecules.

A

10–100 times

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49
Q

When a positively charged region of one water molecule comes close to a negatively charged region of a second water molecule, the electrical attraction between them can establish a weak bond called a ________.

A

hydrogen bond

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50
Q

These bonds are much weaker than covalent bonds and are easily broken by random thermal motions.

A

hydrogen bonds

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51
Q

Such substances are termed _____, meaning that they are “water-loving.”

A

hydrophilic

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52
Q

molecules in the aqueous environment of a cell fall into the hydrophilic category:

A
  • sugars
  • DNA
  • RNA
  • majority of proteins
53
Q

“water-fearing”

A

Hydrophobic

54
Q

are uncharged and form few or no hydrogen bonds, and they do not dissolve in water.

A

Hydrophobic

55
Q

are strongest when the atoms involved are fully charged, as are Na+ and Cl+ ions.

A

Electrostatic attractions

56
Q

a weaker electrostatic attraction can occur between molecules that contain ________.

A

polar covalent bonds

57
Q

A third type of noncovalent bond, called a ______, comes into play when any two atoms approach each other closely.

A

van der Waals attraction

58
Q

These nonspecific interactions spring from fluctuations in the distribution of electrons in every atom, which can generate a transient attraction when the atoms are in very close proximity.

A

van der Waals attraction

59
Q

In an aqueous environment, a ______ is generated by a pushing of nonpolar surfaces out of the hydrogen-bonded water network, where they would otherwise physically interfere with the highly favorable interactions between water molecules.

A

hydrophobic force

60
Q

Hydrophobic forces play an important part in promoting molecular interactions—in particular, in building cell membranes, which are constructed largely from __________ with long hydrocarbon tails.

A

lipid molecules

61
Q

Length and Strength of COVALENT

A
  • 0.10 nm
  • 377 [90] kJ/mole (in vacuum and water)
62
Q

Length and Strength of Noncovalent: IONIC BOND

A
  • 0.25 nm
  • 335 [80] kJ/mole (in vacuum)
  • 12.6 [3] kJ/mole (in water)
63
Q

Length and Strength of Noncovalent: HYDROGEN BOND

A
  • 0.17 nm
  • 16.7 [4] kJ/mole (in vacuum)
  • 4.2 [1] kJ/mole (in water)
64
Q

Length and Strength of Noncovalent: VAN DER WAALS

A
  • 0.35 nm
  • 0.4 [0.1] kJ/mole (in vacuum)
  • 0.4 [0.1] kJ/mole (in water)
65
Q

proton can dissociate from its original partner and associate instead with the oxygen atom of the water molecule, generating a _____.

A

hydronium ion

66
Q

Substances that release protons when they dissolve in water, thus forming H3O+, are termed ______.

A

acids.

67
Q

logarithmic scale

A

pH scale

68
Q

Pure water has a pH of ___ and is thus neutral—that is, neither acidic (pH <7) nor basic (pH >7).

A

7.0

69
Q

Molecules that accept protons when dissolved in water are called _____.

A

bases

70
Q

mixtures of weak acids and bases that will adjust proton concentrations around pH 7 by releasing protons (acids) or taking them up (bases) when- ever the pH changes.

A

buffers

71
Q

carbon-containing compounds

A

organic molecules

72
Q

all other molecules, including water, are said to be ______.

A

inorganic molecules

73
Q

The small organic molecules of the cell are carbon compounds with molecular weights in the range _________ that contain up to 30 or so carbon atoms.

A

100–1000

74
Q

Some are used as _______ subunits to construct the cell’s polymeric macromolecules

A

monomer

75
Q

its proteins, nucleic acids, and large polysaccharides.

A

macromolecules

76
Q

Nearly ______ different kinds of small organic molecules have been detected in the well-studied bacterium Escherichia coli.

A

4000

77
Q

Broadly speaking, cells contain four major families of small organic molecules:

A

the sugars, the
fatty acids, the amino acids, and the nucleotides

78
Q

small organic building blocks of the cell —> larger organic molecules of the cell

A

SUGARS –> POLYSACCHARIDES, GLYCOGEN, AND STARCH (IN PLANTS)

FATTY ACIDS –> FATS AND MEMBRANE LIPIDS

AMINO ACIDS –> PROTEINS

NUCLEOTIDES __> NUCLEIC ACIDS

79
Q

The simplest sugars.

A

monosaccharides

80
Q

Sets of molecules with the same chemical formula but different structures are called ____.

A

isomers

81
Q

mirror-image pairs of such molecules are called

A

optical isomers

82
Q

Monosaccharides can be linked by covalent bonds—called ________ —to form larger carbohydrates.

A

glycosidic bonds

83
Q

Two monosaccharides linked together make a

A

disaccharide

84
Q

Larger sugar polymers range from the _______ (trisaccharides, tetrasaccharides, and so on) up to giant _____, which can contain thousands of monosaccharide subunits (monomers).

A
  • oligosaccharides
  • polysaccharides
85
Q

is used to refer to molecules made of a small number of monomers, typically 2 to 10 in the case of oligosaccharides.

A

oligo

86
Q

a molecule of water is expelled as the bond is formed.

A

condensation reaction

87
Q

The bonds created by all of these condensation reactions can be broken by the reverse process of ______, in which a molecule of water is consumed.

A

hydrolysis

88
Q

The monosaccharide ____ has a central role as an energy source for cells.

A

glucose

89
Q

The most abundant organic molecule on Earth—the _______ that forms plant cell walls—is a polysaccharide of glucose.

A

cellulose

90
Q

Another extraordinarily abundant organic substance, the ______ of insect exoskeletons and fungal cell walls

A

chitin

91
Q

Smaller oligosaccharides can be covalently linked to proteins to form ______.

A

glycoproteins,

92
Q

A fatty acid molecule, such as ______, has two chemically distinct regions.

A

palmitic acid

93
Q

The hydrocarbon tail of palmitic acid is _______: it has no double bonds between its carbon atoms and contains the maximum possible number of hydrogens.

A

saturated

94
Q

Molecules—such as fatty acids—that possess both hydrophobic and hydrophilic regions are termed _______.

A

amphipathic

95
Q

Some other fatty acids, such as oleic acid, have _______ tails, with one or more double bonds along their length.

A

unsaturated

96
Q

Fatty acids are stored in the cytoplasm of many cells in the form of fat droplets composed of ________ molecules.

A

triacylglycerol

97
Q

compounds made of three fatty acid chains covalently joined to a glycerol molecule

A

triacylglycerol

98
Q

loosely defined as molecules that are insoluble in water but soluble in fat and organic solvents such as benzene

A

lipids

99
Q

the structure that forms the basis for all cell membranes

A

lipid bilayer

100
Q

These thin sheets, which enclose all cells and surround their internal organelles, are composed largely of _______.

A

phospholipids

101
Q

are small organic molecules with one defining property: they all possess a carboxylic acid group and an amino group, both attached to a central α-carbon atom

A

Amino acids

102
Q

Cells use amino acids to build

A

proteins

103
Q

polymers made of amino acids

A

proteins

104
Q

The covalent bond between two adjacent amino acids in a protein chain is called a

A

peptide bond

105
Q

the resulting chain of amino acids is therefore also known as a

A

polypeptide

106
Q

are formed by condensation reactions that link one amino acid to the next

A

Peptide bonds

107
Q

Nucleotides containing ribose are known as _____, and those containing deoxyribose are known as ______.

A
  • ribonucleotides
  • deoxyribonucleotides.
108
Q

participates in the transfer of energy in hundreds of metabolic reactions.

A

adenosine triphosphate, or ATP

109
Q

is formed through reactions that are driven by the energy released from the break- down of foodstuffs

A

ATP

110
Q

long polymers in which nucleotide subunits are linked by the formation of covalent phosphodiester bonds

A

nucleic acid

111
Q

are constructed simply by covalently linking small organic monomers, or subunits, into long chains, or polymers

A

macromolecules

112
Q

The vast majority of the dry mass of a cell consists of macromolecules

A

mainly polysaccharides, proteins, and nucleic acids (DNA and RNA)

113
Q

forms when two atoms come very close together and share one or more of their outer-shell electrons.

A

covalent bond

114
Q
A
115
Q

Carbon and hydrogen together make stable compounds (or groups) called

A

hydrocarbons

116
Q

These are nonpolar, do not form hydrogen bonds, and are generally insoluble in water.

A

C-H Compounds

117
Q

the bonding electrons move within the molecule, stabilizing the structure by a phenomenon called ______.

A

resonance

118
Q

The –OH is called a ______ group.

A

hydroxyl

119
Q

The C = O is called a _____ group.

A

carbonyl

120
Q

The –COOH is called a __________ group.

A

carboxyl

121
Q

are formed by combining an acid and an alcohol.

A

Esters

122
Q

are formed by combining an acid and an amine.

A

amides

123
Q

Inorganic phosphate is a stable ion formed from

A

phosphoric acid

124
Q

can form between a phosphate and a free hydroxyl group

A

Phosphate esters

125
Q

are often covalently attached to proteins in this way.

A

Phosphate groups

126
Q

Substances that release hydrogen ions (protons) into solution are called

A

acids.

127
Q

Many of the acids important in the cell are not completely dissociated, and they are therefore

A

weak acids

128
Q

_______ occur both between
fully charged groups (ionic bond) and between partially charged groups on polar molecules.

A

Electrostatic attractions

Cell and Molecular Biology (6 decks)

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