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Biochemistry > Chapter 3 > Flashcards

Chapter 3 Flashcards

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1
Q

(-) Delta G = free energy ______
This is _______ process.

A
  • is available to do work (favored)
    exergonic
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2
Q

+ Delta G = free energy is _____
This is called ________ process.

A
  • required (not favored)
  • endergonic
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3
Q

K is > than Q

A

Reverse reaction (reactants formed)

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4
Q

K is < than Q

A

Forward reaction (products are formed)

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5
Q

What is an open system?

A

A system that exchanges both matter and energy with its surroundings.

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6
Q

What is a closed system?

A

A system that exchanges only energy, not matter, with its surroundings.

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7
Q

What is an isolated system?

A

A system that exchanges neither matter nor energy with its surroundings.

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8
Q

Which type of system best describes living systems?

A

Open system.

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9
Q

What does the First Law of Thermodynamics state?

A

Energy is conserved; it cannot be created or destroyed, only transferred as heat or work.

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10
Q

What is enthalpy (ΔH)?

A

Heat exchanged between a system and its surroundings at constant pressure.

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11
Q

What is entropy (ΔS)?

A

A measure of disorder or randomness in a system.

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12
Q

What is Gibbs free energy (ΔG)?

A

Energy available to do useful work at constant temperature and pressure.

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13
Q

What is the formula for Gibbs free energy?

A

ΔG = ΔH – TΔS

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14
Q

What does a negative ΔG indicate?

A

A favorable, spontaneous (exergonic) reaction.

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15
Q

What does a positive ΔG indicate?

A

An unfavorable, non-spontaneous (endergonic) reaction.

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16
Q

What is true about ΔG at equilibrium?

A

ΔG = 0 at equilibrium.

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17
Q

What does a large equilibrium constant (K) imply?

A

Products are favored.

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18
Q

What does a small equilibrium constant (K) imply?

A

Reactants are favored.

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19
Q

What is the Reaction Quotient (Q)?

A

A ratio of products to reactants at any point, not just equilibrium.

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20
Q

If Q < K, which direction does the reaction proceed?

A

Forward direction (toward products).

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21
Q

If Q > K, which direction does the reaction proceed?

A

Reverse direction (toward reactants).

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22
Q

How is the standard free energy change (ΔG°′) different from ΔG°?

A

ΔG°′ is adjusted for biological conditions: pH 7, constant [H₂O].

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23
Q

Why is ΔG°′ used in biochemistry?

Study These Flashcards
A

It reflects biological conditions such as pH 7 and constant water concentration.

24
Q

What is the relationship between ΔG and Q?

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A

ΔG = ΔG°′ + RT ln(Q)

25
What is the relationship between ΔG°′ and K?
ΔG°′ = –RT ln(K)
26
What does coupling a favorable and an unfavorable reaction achieve?
It drives the unfavorable reaction forward.
27
What is the ΔG°′ of ATP hydrolysis?
–32.2 kJ/mol
28
How does ATP hydrolysis help cells?
It provides energy to drive unfavorable reactions.
29
What happens to ΔG when moving down a concentration gradient?
ΔG is negative (favorable).
30
What happens to ΔG when moving against a concentration gradient?
ΔG is positive (requires energy input).
31
What happens to entropy in an isolated system over time?
Entropy increases to a maximum value.
32
How does a cell maintain homeostasis?
By keeping Q far from K and using energy to maintain steady states.
33
What is true of ΔG in homeostasis?
ΔG < 0 (not at equilibrium).
34
What is oxidation?
Loss of electrons.
35
What is reduction?
Gain of electrons.
36
What formula links free energy to redox potentials?
ΔG°′ = –nFΔE°′
37
What is Faraday’s constant (F)?
96.5 kJ/mol·V
38
What is ΔE°′?
Difference in standard reduction potentials between electron donor and acceptor.
39
What does a higher E°′ mean?
A stronger tendency to accept electrons (stronger oxidizing agent).
40
In a redox reaction, what is the electron donor called?
Reducing agent.
41
In a redox reaction, what is the electron acceptor called?
Oxidizing agent.
42
If entropy (ΔS) decreases and enthalpy (ΔH) increases, what happens to ΔG?
ΔG becomes more positive (reaction becomes less favorable).
43
If temperature (T) increases in a system where ΔS is positive, how does ΔG change?
ΔG becomes more negative (reaction becomes more favorable).
44
If the concentration of products increases, how does Q change?
Q increases.
45
If Q increases and becomes greater than K, what happens to the reaction direction?
Reaction shifts toward reactants (reverse reaction favored).
46
If Q decreases and is less than K, what happens to the reaction direction?
Reaction shifts toward products (forward reaction favored).
47
If the reaction is at equilibrium, what is the value of ΔG?
ΔG = 0.
48
If a reaction has a large, positive ΔG°′, what must happen to Q to make ΔG negative?
Q must be made very small (decrease product concentration, increase reactant concentration).
49
If a system becomes more disordered, what happens to entropy (ΔS)?
Entropy (ΔS) increases.
50
If a process releases heat into the surroundings, what is the sign of ΔH?
ΔH is negative (exothermic).
51
If ΔH is negative and ΔS is positive, is the reaction spontaneous?
Yes, the reaction is always spontaneous under these conditions.
52
If ΔG is positive, what must be true about the relationship between ΔH and TΔS?
ΔH > TΔS (enthalpy dominates and is unfavorable).
53
If ΔE°′ is positive in a redox reaction, what is the sign of ΔG°′?
ΔG°′ is negative (favorable reaction).
54
If an oxidizing agent becomes stronger, what happens to its E°′ value?
E°′ increases (greater tendency to accept electrons).
55
If a system does work on its surroundings without absorbing heat, what happens to its internal energy?
Internal energy decreases.
56
In a closed system, if no work is done and no heat is exchanged, what happens to internal energy?
Internal energy remains constant.

Biochemistry (7 decks)

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