CH 3 Flashcards

1
Q

Your body extracts energy from the food you ingest by catalyzing reactions that essentially “burn” the food molecules in a stepwise fashion. What is another way to describe this process?

A

oxidation

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2
Q

Oxidation is a favorable process in an aerobic environment, which is the reason cells can derive energy from the oxidation of macromolecules. Once carbon has been oxidized to __________, its most stable form, it can only cycle back into the organic portion of the carbon cycle through __________.

A

CO2, photosynthesis

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3
Q

For the reaction Y → X at standard conditions with [Y] = 1 M and [X] = 1 M, ΔG is initially a large negative number. As the reaction proceeds, [Y] decreases and [X] increases until the system reaches equilibrium. How do the values of ΔG and ΔG° change as the reaction equilibrates?

A

ΔG becomes less negative and ΔG° stays the same.

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4
Q

The equilibrium constant (K) for the reaction Y → X can be expressed with respect to the concentrations of the reactant and product molecules. Which of the expressions below shows the correct relationship between K, [Y], and [X]?

A

K = [X]/[Y]

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5
Q

If proteins A and B have complementary surfaces, they may interact to form the dimeric complex AB. Which of the following is the correct way to calculate the equilibrium constant for the association between A and B?

A

K = [AB]/[A][B]

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6
Q

NADH and NADPH are activated carrier molecules that function in completely different metabolic reactions. Both carry two additional __________ and one additional __________. This combination can also be referred to as a hydride ion.

A

electrons, proton

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7
Q

T / F
Activated carriers provide energy for unfavorable reactions and are “reloaded” when coupled to favorable reactions.

A

True

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8
Q

Chemical reactions are reversible; they can proceed in both the forward and reverse directions. If the ΔG° for the reaction Y → X is energetically favorable, how can you explain the fact that not all the Y molecules will be converted to X molecules?

A

As Y -> X, the [Y] decreases and [X] increases, which makes ΔG less negative and the reaction less favorable as the reaction nears equilibrium.

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9
Q

Heat:

A

form of energy arising from random motion of molecules

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10
Q

Entropy:

A

measure of disorder

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11
Q

Enzyme use in redox reactions

A

catalysts that transfer electrons to make/break bonds

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12
Q

Addition of hydrogens is…

A

reduction

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13
Q

Removal of hydrogens is…

A

oxidation

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14
Q

equilibrium constant is directly proportional to…

A

delta G°

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15
Q

delta G =

A

(c+d) - (a+b)

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16
Q

enzymes can speed up rate but cannot change the

17
Q

why do we need energy

A

to perform unfavorable reactions through coupling

18
Q

Delta G equation

A

G = G° + RT ln [Prod]/[React]

19
Q

delta G° is________ of concentration

A

independent ~ only intrinsic properties of products + reactants

20
Q

The Equilibrium Constant (K) Is Directly Proportional to delta G°

A

-5.94 log K

21
Q

Sequential reactions

A

X -> Y unfavorable (+delta G)
Y -> Z very favorable (-delta G)

Y -> Z reaction siphons the X-Y reaction

22
Q

In general, enzymes and substrates are found in relatively _____ concentrations to water

23
Q

the larger K, the greater distance between associated and dissociated states, leading to a ____ binding site interaction between the two molecules

24
Q

siphoning reaction

A

Siphoning, where a favorable reaction lowers the concentration of the product of an
unfavorable reaction, driving the reaction to occur

25
Q

Nad+
NADPH

A

NAD+ - oxidizing agent in catabolic reactions that generate ATP
NADPH - reducing agent in anabolic reactions

26
Q

Condensation vs hydrolysis

A

Condensation - lost of H2O ~ unfavorable
Hydrolysis - gain of H2O ~ favorable