Hamdan- Bioenergetics

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Questions and Answers

What is the primary role of ATP in cellular metabolism?

To provide energy for unfavorable biochemical reactions (correct)
To facilitate the transfer of phosphate groups
To store energy from exergonic reactions
To act as a reducing agent in redox reactions

Which of the following statements about the free energy change ($\Delta G$) of a reaction is correct?

$\Delta G$ is constant for a given reaction, regardless of conditions
$\Delta G$ is additive for coupled reactions (correct)
$\Delta G$ is always negative for spontaneous reactions
$\Delta G$ is independent of substrate and product concentrations

What is the primary function of activated intermediates like ATP in metabolism?

To store energy from exergonic reactions
To facilitate the transfer of specific groups between molecules (correct)
To act as reducing agents in redox reactions
To increase the entropy of the system

What is the principle behind thermogenesis in living organisms?

Heat production is a consequence of exergonic reactions (D) Signup and view all the answers

In a redox reaction, what determines the direction of electron flow?

The reduction potential of the oxidant and reductant (D) Signup and view all the answers

What is the primary role of coenzyme A (CoA) in metabolism?

To facilitate the transfer of acyl groups (C) Signup and view all the answers

What happens to the value of ΔG° when the equilibrium constant (K_eq) is greater than 1?

ΔG° is negative (D) Signup and view all the answers

Which of the following statements about ΔG and K_eq is true?

ΔG is additive for multiple subsequent reactions, while K_eq is multiplicative (A) Signup and view all the answers

When a stress is applied to a system at equilibrium, how does the equilibrium shift?

The equilibrium shifts to relieve the stress (D) Signup and view all the answers

What is the effect of continuously supplying or removing a reactant or product on a metabolic reaction?

The reaction takes advantage of this effect to proceed (B) Signup and view all the answers

How does an increase in temperature affect an endothermic reaction at equilibrium?

It favors the forward reaction (B) Signup and view all the answers

What is the role of ATP in cellular energy transformations?

ATP both stores and releases energy for metabolic reactions (D) Signup and view all the answers

What is the definition of bioenergetics according to the text?

The study of energy transformations in living cells and the chemical processes underlying them. (B) Signup and view all the answers

According to the first law of thermodynamics, what happens to the total amount of energy in the universe during any change?

It remains constant. (B) Signup and view all the answers

What does the second law of thermodynamics say about the tendency of the universe?

The universe always tends toward increasing disorder or entropy. (C) Signup and view all the answers

What is the relationship between $ ext{Δ}G$ and $ ext{Δ}G^{o}$?

$ ext{Δ}G$ is affected by the concentration of reactants and products, while $ ext{Δ}G^{o}$ is not. (C) Signup and view all the answers

What is the relationship between the combustion of glucose in a calorimeter and the conversion of glucose to CO2 and H2O in a cell?

The energy released is the same in the two processes. (C) Signup and view all the answers

How does $ ext{Δ}G$ measure the tendency of a reaction to proceed towards equilibrium?

$ ext{Δ}G$ measures the spontaneity of the reaction, with negative values indicating a spontaneous reaction. (C) Signup and view all the answers

Which equation represents the relationship between the standard free-energy change (Go) and the equilibrium constant (Keq)?

$ext{}G^{o} = RText{ln}ext{K}_{eq}$ (D) Signup and view all the answers

What is the value of G when the concentrations of reactants and products are both 1 mol/L?

G = Go (D) Signup and view all the answers

What is the sign of G when the reaction is at equilibrium?

G is zero (A) Signup and view all the answers

What is the relationship between the sign of Go and the value of the equilibrium constant (Keq)?

If Go is negative, then Keq < 1 (B) Signup and view all the answers

What is the value of G when the concentrations of glucose 6-phosphate and fructose 6-phosphate are 0.66 mol/L and 0.33 mol/L, respectively?

G = Go + RT ln (0.33/0.66) (A) Signup and view all the answers

What is the sign of G when the reaction is not at equilibrium?

G can be positive, negative, or zero (D) Signup and view all the answers

What is the relationship between G and the direction of a reaction?

A negative G means the reaction is spontaneous (D) Signup and view all the answers

Can a reaction have a positive Go and still be favorable?

Yes, if the reaction is coupled to another favorable reaction (D) Signup and view all the answers

What does the second law of thermodynamics state?

The universe always tends toward increasing disorder (or entropy). (D) Signup and view all the answers

Which statement about $\Delta G$ is true?

$\Delta G$ is a state function that depends only on the initial and final states. (D) Signup and view all the answers

What is the relationship between $\Delta G$ and the spontaneity of a reaction?

A negative $\Delta G$ indicates a spontaneous reaction. (D) Signup and view all the answers

What is the effect of increasing the concentration of products on the value of $\Delta G$?

$\Delta G$ increases. (A) Signup and view all the answers

What does the first law of thermodynamics state?

For any change, the total amount of energy in the universe remains constant. (D) Signup and view all the answers

What is the relationship between $\Delta G^{\circ}$ and the equilibrium constant ($K_{eq}$)?

All of the above. (D) Signup and view all the answers

What is the concept of activation energy?

The energy required to initiate a chemical reaction. (A) Signup and view all the answers

What is the relationship between the combustion of glucose in a calorimeter and the conversion of glucose to CO2 and H2O in a cell?

The $\Delta G$ values are the same. (A) Signup and view all the answers

Where in the body are mitochondria found in the greatest number?

Eye, brain, heart, and muscle (D) Signup and view all the answers

What is the primary function of mitochondria?

ATP production (A) Signup and view all the answers

Why is ATP considered a high-energy molecule?

It has an intermediate energy value, allowing it to be coupled to other reactions (C) Signup and view all the answers

Which of the following statements about ATP is true?

It is recycled as food in cells is gradually oxidized (C) Signup and view all the answers

What is the total daily ATP turnover in the human body, in grams?

49,920 g (C) Signup and view all the answers

Which of the following statements about biochemical reactions and pathways is true?

They are coordinated by sensitive means of communication (D) Signup and view all the answers

Which of the following is an example of an exergonic reaction or pathway in biochemistry?

Oxidation of glucose with oxygen to carbon dioxide and water (C) Signup and view all the answers

How do cells obtain energy for unfavorable biochemical work?

By coupling unfavorable reactions to exergonic reactions (D) Signup and view all the answers

Which of the following is true about the free energy change ($\Delta$G) of a reaction?

$\Delta$G depends on the concentrations of reactants and products, not just on temperature and pressure. (A) Signup and view all the answers

What is the primary role of ATP in cellular metabolism?

To store energy from exergonic reactions for use in endergonic reactions. (D) Signup and view all the answers

What is the primary function of activated intermediates like ATP in metabolism?

To store energy for later use in endergonic reactions. (C) Signup and view all the answers

What is the principle behind thermogenesis in living organisms?

Thermogenesis is the process of generating heat as a byproduct of metabolism. (A) Signup and view all the answers

What is the relationship between $\Delta$G and $\Delta$G$^{\circ}$?

$\Delta$G = $\Delta$G$^{\circ}$ + RT ln K${eq}$, where K${eq}$ is the equilibrium constant. (A) Signup and view all the answers

What is the primary role of coenzyme A (CoA) in metabolism?

To act as a universal carrier of acyl groups. (C) Signup and view all the answers

In a redox reaction, what determines the direction of electron flow?

The reduction potentials of the oxidant and reductant. (A) Signup and view all the answers

What is the relationship between the combustion of glucose in a calorimeter and the conversion of glucose to CO2 and H2O in a cell?

The combustion in a calorimeter measures the total energy released, while the cellular process measures the free energy change. (C) Signup and view all the answers

What is the relationship between the Gibbs free energy change ($\Delta G^{\circ}$) and the equilibrium constant ($K_{eq}$)?

$\Delta G^{\circ} = - RT \ln K_{eq}$ (C) Signup and view all the answers

How does the value of $\Delta G^{\circ}$ change with respect to the equilibrium constant ($K_{eq}$)?

All of the above statements are true (D) Signup and view all the answers

What happens to the equilibrium of a reaction when a reactant or product is continuously supplied or removed?

The equilibrium shifts to favor the formation of more products (C) Signup and view all the answers

How does an increase in temperature affect an endothermic reaction at equilibrium?

It favors the forward reaction (C) Signup and view all the answers

What is the effect of a catalyst on an equilibrium reaction?

It has no effect on the equilibrium position (B) Signup and view all the answers

What is the role of ATP in cellular metabolism?

It acts as a carrier of energy for metabolic reactions (B) Signup and view all the answers

According to the first law of thermodynamics, what happens to the total amount of energy in the universe during any change?

The total amount of energy remains constant (A) Signup and view all the answers

What is the primary role of coenzyme A (CoA) in metabolism?

It is a carrier of acetyl groups and other acyl groups (B) Signup and view all the answers

Flashcards

Bioenergetics

The study of energy transductions in living cells and the chemical processes involved.

First Law of Thermodynamics

Total energy in the universe remains constant; energy can only be transformed.