Chapter 14 Flashcards
1
Q
the free energy released from catabolic oxidation reactions is used to driver …
A
endergonic anabolic rxns
2
Q
nutrition is the intake and utilization of food to supply … and …
A
free energy; raw materials
3
Q
heterotrophic organisms obtain their free energy from compounds synthesized by … or … organisms
A
chemolithotrophic; photoautotrophic
4
Q
food contains …, …, …, …, …, and …
A
proteins; carbohydrates; fats; water; vitamins; minerals
5
Q
metabolic pathways are sequences of enzyme-catalyzed reactions that occur in
A
different cellular locations
6
Q
near-equilibrium reactions are …, whereas reactions that function far from equilibrium serve as … points and render metabolic pathways …
A
freely reversible; regulatory; irreversible
7
Q
flux through a metabolic pathway is controlled by regulating the activities of the enzymes that catalyze its
A
rate-determining steps
8
Q
the free energy of the “high-energy” compound ATP is made available through cleavage of one or both of its ….
A
phosphoanhydride bonds
9
Q
an exergonic rxn such as ATP or PPi hydrolysis can be coupled to an … rxn to make it more favorable
A
endergonic
10
Q
substrate-level phosphorylation is the synthesis of ATP from … by … from another compound
A
ADP; phosphoryl group transfer
11
Q
the common product of carbohydrate, lipid, and protein catabolism, …, is a “high-energy” …
A
acetyl-CoA; thioester
12
Q
the coenzymes … and … are reversibly reduced during the oxidation of metabolites
A
NAD+; FAD
13
Q
the Nernst equation relates the electromotive force of a redox rxn to the … and concentrations of the … and …
A
standard reduction potentials; electron donors; acceptors
14
Q
electrons flow spontaneously from the reduced member of a redox couple with the … to the oxidized member of a redox couple with the …
A
lower reduction potential; higher reduction potential
15
Q
studies of metabolic pathways determine the order of metabolic transformations, their …, their …, and their … to metabolic processes in other tissues
A
enzymatic mechanisms; regulation; relationships
16
Q
metabolic pathways are studied using … and … tracers, …, natural and engineered …, …, and … techniques
A
isotopic; fluorescent; enzyme inhibitors; mutations; DNA microarrays; proteomics
17
Q
systems biology endeavors to quantitatively describe the properties and dynamics of biological networks as a whole through the integration of …, …, …, and … information
A
genomic; transcriptomic; proteomic; metabolomic
18
Q
…: the overall process through which living systems acquire and use free energy to carry out their various functions
A
metabolism
19
Q
…, or degradation, in which nutrients and cell constituents are broken down to salvage their components and/or to make energy available
A
catabolism
20
Q
…, or biosynthesis, in which biomolecules are synthesized from simpler components
A
anabolism
21
Q
in general, catabolic rxns carry out the … of nutrient molecules
A
exergonic oxidation
22
Q
…, the intake and utilization of food; affects health, development, and performance
A
nutrition
23
Q
some prokaryotes are …, which can synthesize all their cellular constituents from simple molecules such as H2O, CO2, NH3, and H2S
A
autotrophs
24
Q
… obtain their energy through the oxidation of inorganic compounds such as NH3, H2S, or even Fe2+
A
chemolithotrophs
25
… obtain energy via photosynthesis, a process in which light energy powers the transfer of electrons from inorganic donors to CO2 to produce carbohydrates, which are later oxidized to release free energy
photoautotrophs
26
… obtain free energy through the oxidation of organic compounds (carbs, lipids, and proteins) and hence ultimately depend on … for those substances
heterotrophs; autotrophs
27
… must use o2, whereas … employ oxidizing agents such as sulfate or nitrate
obligate aerobes; anaerobes
28
…, such as E. coli, can grow in either the presence or the absence of O2. …, in contrast, are poisoned by the presence of O2.
facultative anaerobes; obligate anaerobes
29
animals are obligate …, whose nutrition depends on a balanced intake of the … proteins, carbs, and lipids
aerobic heterotrophs; macronutrients
30
the metabolic utilization of macronutrients also requires the intake of O2 and water, as well as … composed of … and …
micronutrients; vitamins; minerals
31
Vitamins can be divided into two groups: … vitamins and … vitamins
water-soluble; fat-soluble
32
```
water-soluble vitamins:
…
…
…
…
…
…
…
…
…
```
```
biotin (b7_
pantothenic acid (B5_
cobalamin (B12)
riboflavin (b2)
nicotinamide (niacin; B3)
pyridoxine (B6)
Folic acid (B9)
thiamine (B1)
ascorbic acid (C)
```
33
```
fat-soluble vitamins:
…
…
…
...
```
vit A
vit D
vit E
vit K
34
the NAD+ component …, or its carboxylic acid analog .. (niaci), relieves the ultimately fatal dietary deficiency disease in humans known as pellagra
nicotinamide; nicotinic acid
35
most animals, including humans, can synthesize nicotinamide from the amino acid ...
tryptophan
36
… are series of connected enzymatic rxns that produce specific products. their reactants, intermediates, and products are referred to as ...
metabolic pathways; metabolites
37
in degradative pathways, the major nutrients, referred to as …, are exergonically broken down into simpler products. the free energy released in the degradative process is conserved by synthesis of ATP, or by the reduction of a coenzyme such as NADP+
complex metabolites
38
the pathways for the catabolism of a large number of diverse substances (carbs, lipids, and proteins) converge on a few …, in many cases a two carbon acetyl unit linked to coenzyme A, to form …
common intermediates; acetyl-coenzyme A
39
when one substances is oxidized (loses e-), another must be … (gain 3-)
reduced
40
relatively few … serve as starting materials for a host of varied products
metabolites
41
rxns catalyzed by the six classes of enzymes
… and … (catalyzed by oxidoreductases)
… (catalyzed by transferases and hydrolases)
…
…
…. (catalyzed by isomerases and mutases)
reactions that … or … (catalyzed by hydrolases, lyases, and ligases)
```
oxidations; reductions
group-transfer rxns
eliminations
isomerizations
rearrangements
make or break C-C bonds
```
42
electron transport and oxidative phosphorylation occur in the …, whereas glycolysis ( a carbohydrate degradation pathway) and fatty acid biosynthesis occur in the ...
mitochondria; cytosol
43
the synthesis of metabolites in specific membrane-bounded compartments in eukaryotic cells requires … to … these substances between compartments. accordingly, … are essential components of many metabolic processes
mechanisms; transport; transport proteins
44
…: enzymes that catalyze the same rxn but are encoded by different genes and have different kinetic/regulatory properties
isozymes
45
example of isozyme:
| vertebrates possess two homologs of the enzyme …, which catalyzes the interconversion of pyruvate and lactate
lactate dehydrogenase
46
many metabolic rxns are said to be …, bc their delta g values are close to zero, and they can be relatively easily reversed by changing the ratio of products to reactants
near-equilibrium rxns
47
enzymes that catalyze near-equilibrium rxns tend to act quickly to restore …, and the net rates of such rxns are effectively controlled by the relative concentrations of … and …
equilibrium concentrations; substrates; products
48
for enzymes that work on rxns operating far from equilibrium, only changes in the … of the enzyme can significantly alter the rate. the enzyme controls the flow of substrate through the reaction by …, much as a dam controls the flow of a river by varying the opening of its floodgates
activity; varying its activity
49
…: rate of flow of metabolites through a metabolic pathway
flux
50
metabolic pathways are … --> a highly exergonic rxn is irreversible. if such a rxn is part of a multistep pathway, it confers … on the pathway; that is, it makes the entire pathway irreversible
irreversible; directionality
51
every metabolic pathway has a first … --> although most rxns in a metabolic pathway function close to equilibriu, there is generally an irreversible rxn early in the pathway that commits its product to continue down the pathway
committed step
52
… and … pathways differ
catabolic; anabolic
53
the existence of independent interconversion routes is an important property of metabolic pathways bc it allows … of the two processes
independent control
54
the flux of intermediates through a metabolic pathway in a steady state is more or less …; that is the rates of synthesis and breakdown of each pathway intermediate maintain it at a …
constant; constant concentration
55
the flux of metabolites, J, through each rxn step is the rate of the forward rxn, vf, less that of the reverse rxn, vr:
…
J = vf - vr
56
At equilibrium, by definition, there is no flux (J = 0), although vf and vr may be quite large. In reactions that are far from equilibrium, vf ≫ vr, the flux is essentially equal to the ...
rate of the forward reaction (J ≈ vf).
57
the rate determining step functions far from … and has a large negative ...
equilibrium; free energy change
58
(mechanisms to control flux through rate-determining steps)
1. … control
2. … modification (e.g. phosphorylation/dephosphorylation)
3. …, where vf and vr may be independently varied
4. … control
allosteric
covalent
substrate cycles
genetic
59
a metabolic pathway is part of a … process
supply-demand
60
Oxidative metabolism proceeds in a stepwise fashion, so the released free energy can be recovered in a manageable form at each exergonic step of the overall process. These “packets” of energy are conserved by the synthesis of a few types of ... whose subsequent exergonic breakdown drives endergonic processes.
“high-energy” intermediates
61
ATP consists of an … moiety (adenine + ribose) to which … groups are sequentially linked via .. bond followed by two … bonds
adenosine; three phosphoryl; a phosphoester; phosphoanhydride
62
..: measure of the tendency of phosphorylated compounds to transfer their phosphoryl groups to water
phosphoryl group-transfer potentials
63
a favorable free energy change for a rxn does not indicate how … the rxn occurs.
quickly
64
(reasons for high energy character of phosphoanhydride bonds) . The resonance stabilization of a phosphoanhydride bond is less than that of its hydrolysis products. This is because a phosphoanhydride’s two strongly electron-withdrawing groups must compete for the lone pairs of electrons of its bridging oxygen atom, whereas this competition is absent in the hydrolysis products. In other words, the electronic requirements of the phosphoryl groups are less satisfi ed in a ...than in its ...
phosphoanhydride; hydrolysis products
65
(reasons for high energy character of phosphoanhydride bonds) Of perhaps greater importance is the destabilizing effect of the ....between the charged groups of a phosphoanhydride compared to those of its hydrolysis products. In the physiological pH range, ATP has three to four negative charges whose mutual electrostatic repulsions are partially relieved by ATP hydrolysis.
electrostatic repulsions
66
(reasons for high energy character of phosphoanhydride bonds) Another destabilizing influence, which is difficult to assess, is the smaller ... of a phosphoanhydride compared to that of its hydrolysis products. Some estimates suggest that this factor provides the dominant thermodynamic driving force for the hydrolysis of phosphoanhydrides
solvation energy
67
as long as the overall pathway is exergonic, it will ...
operate in the forward direction
68
the initial step in the metabolism of glucose is its conversion to ...
glucose-6-phosophate
69
atp can be regenerated by coupling its synthesis from ADP and Pi to the more exergonic cleavage of ...
phosphoenolpyruvate
70
…, the enzyme that catalyzes the formation of glucose-6-phosphate does not catalyze ATP hydrolysis but instead catalyzes the transfer of a phosphoryl group from ATP directly to glucose
hexokinase
71
…, transfers a phosphoryl group from phosphoenolpyruvate to ADP to form ATP
pyruvate kinase
72
in processes of ATP hydrolysis, proteins undergo conformational changes in response to binding ATP. the exergonic hydrolysis of ATP and release of ADP and Pi renders these changes … and thereby drives the processes forward
irreversible
73
ATP hydrolysis is … favored but … disfavored
thermodynamically; kinetically
74
although many rxns involve ATP yield ADP and Pi (…), others yield AMP and PPi (…)
orthophosphate cleavage; pyrophosphate cleavage
75
the pyrophosphate cleavage of ATP ultimately consumes two
high energy phosphoanhydride bonds
76
atp is continually being … and ..
hydrolyzed; regenerated
77
atp itself can be regenerated by coupling its formation to a more
highly exergonic metabolic process
78
other mechanisms generate ATP indirectly, using the energy supplied by transmembrane proton concentration gradients. in oxidative metabolism, this process is called … whereas in photosynthesis, it is termed ...
oxidative phosphorylation; photophosphorylation
79
…: enzymes that transfer phosphoryl groups from ATP to other compounds or from phosphorylated compounds to ADP
kinases
80
muscle and nerve cells, which have a high ATP turnover, rely on … to regenerate ATP rapidly
phosphoguanidines
81
the phosphorylation of creatine by creatine kinase is endergonic under standard conditions; however, the intracellular concentrations of its reactants and products are such that it operates
close to equilibrium
82
… acts as an ATP "buffer" in cells that contain ...
phosphocreatine; creatine kinase
83
...: a phosphoguanidine whose phosphoryl group transfer potential is greater than that of ATP; these compounds can therefore phosphorylate ADP to generate ATP
phosphagen
84
... are synthesized from ATP and the corresponding ... in a rxn catalyzed by the nonspecific enzyme ...:
ATP + NDP ADP + NTP
nucleoside triphosphates; nucleoside diphosphate; nucleoside diphosphate kinase
85
the ... bond is involved in substrate-level phosphorylation, an TP generating process that is independent of- and presumably arose before- oxidative phosphorylation
thioester
86
... consists of a beta-mercaptoethylamine group bonded through an amide linkage to the vitamin ... which is attached to a 3'-phosphoadenosine moiety via a pyrophosphate bridge (LOOK AT CELL MOLEC Q)
coenzyme A; pantothenic acid;
87
CoA functions as a carrier of ... and other ... groups
acetyl; acyl
88
a ... or ... agent is an electron donor
| an ... or ... agent is an electron acceptor
reductant; reducing
| oxidant; oxidizing
89
redox rxns can be divided into two ...
half-rxns
90
a half rxn consists of an e... and its conjugate ...
electron donor; electron acceptor
91
the electron donor and conjugate electron acceptor constitue a ... or ... analogous to a conjugate acid-base pair
redox couple; conjugate redox pair
92
the two half-rxns of a redox rxn, each consisting of a conjugate redox pair, can be physically separated to form an ..
.electrochemical cell
93
....: the tendency for a substance to undergo reduction (gain electrons)
reduction potential
94
...: electron pressure that the electrochemical cell exerts
electromotive force (emf)
95
a positive electromotive force indicates a ... rxn, one that can do work
spontaneous rxn
96
the more positive the standard reduction potential, the higher the affinity of the redox couple's oxidized form for ...; that is, the greater the tendency for the redox couple's oxidized form to ... and thus become ...
electrons; accept electrons; reduced
97
the protein components of redox enzymes play active roles in ... by modulating the ... of their bound redox-active centers
electron-transfer rxns; reduction potentials
98
NADH functions as an energy rich ...
e- transfer coenzyme
99
the oxidation by o2 of one NADH to NAD+ supplies sufficient free energy to generate almost ...
3 ATPs
100
a metabolic pathway can be understood in terms of the sequence of rxns by which a specific nutrient is ... and the ... of the conversions
converted to end products; energetics
101
a metabolic pathway can be understood in terms of the mechanisms by which each intermediate is converted to its ...
successor
102
a metabolic pathway can be understood in terms of the ... that regulate the flow of metabolites through the pathway
control mechanisms
103
the fate of an isotopically labeled atom in a metabolite can be elucidated by following its progress through the
metabolic pathway of interest
104
one way to perturb a pathway is to add certain substances, called ..., that block the pathway at specific points, thereby causing the preceding intermediates to build up
metabolic inhibitors
105
the basic metabolic pathways in most organisms are essentially
identical
106
...: chemical agents that induce genetic changes
mutagens
107
... the entire collection of RNA transcribed by a cell
transcriptome
108
...: the complete set of proteins synthesized by a cell in response to changing conditions
proteome
109
...: the cell's collection of metabolic intermediates
metabolome
110
... or ... are made by depositing numerous diff DNA segments of known gene sequences in a precise array on a solid support such as a coated glass surface. these are often PCR-amplified cDNA clones derived from mRNAs
DNA microarrays; DNA chips
