Biochemistry: Energy Production and ATP Synthesis

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Questions and Answers

What is the energy requirement for the reaction ADP + Pi → ATP?

+10.3 kcal/mol

-7.3 kcal/mol

+7.3 kcal/mol (correct)

-3 kcal/mol

What type of reaction is ATP → ADP + Pi characterized as?

Irreversible

Reversible

Exergonic (correct)

Endergonic

What is the surplus energy released as heat when synthesizing ATP from creatine phosphate?

+10.3 kcal/mol

-3 kcal/mol (correct)

-10.3 kcal/mol

+7.3 kcal/mol

What is the energy change associated with the reverse reaction of creatine to creatine phosphate?

+10.3 kcal/mol (B) Signup and view all the answers

What indicates that a reaction is exergonic?

Negative ΔG (A) Signup and view all the answers

How much energy is released when hydrolyzing creatine phosphate?

-10.3 kcal/mol (A) Signup and view all the answers

Why is the energy free for the reaction creatine to creatine phosphate not sufficient to proceed?

Energy produced is less than +3 kcal/mol (B) Signup and view all the answers

What can be inferred about the high-energy phosphate bonds from the reactions described?

Hydrolysis of these bonds releases energy (B) Signup and view all the answers

What is the main purpose of oxidative phosphorylation?

To generate ATP driven by electrons from substrate oxidation. (A) Signup and view all the answers

Which complexes in the electron transport chain use energy to pump protons to the intermembrane space?

Complex I, III, and IV (C) Signup and view all the answers

How is the electrochemical potential (proton-motive force) created during oxidative phosphorylation?

Through the translocation of protons across the mitochondrial membrane. (B) Signup and view all the answers

Which of the following statements about the chemiosmotic coupling theory is true?

It links electron transfer with proton translocation across the membrane. (A) Signup and view all the answers

Where do NADH and FADH2 primarily get produced in the context of oxidative phosphorylation?

In glycolysis, TCA cycle, and beta-oxidation. (C) Signup and view all the answers

What role does ATP synthase (Complex V) play in oxidative phosphorylation?

It facilitates the entry of protons and synthesizes ATP. (D) Signup and view all the answers

Which complex is NOT involved in proton pumping during oxidative phosphorylation?

Complex II (C) Signup and view all the answers

What is the primary source of electrons for the electron transport chain?

NADH and FADH2 generated during metabolic processes. (B) Signup and view all the answers

What type of reaction is A → B described as?

Exergonic (C) Signup and view all the answers

What happens to the free energy when the reaction A → B occurs?

It is released as heat. (D) Signup and view all the answers

What is the purpose of transforming energy from A → B into ATP?

To store energy for later use. (D) Signup and view all the answers

What type of phosphorylation occurs when ADP is phosphorylated to form ATP using creatine phosphate?

Substate-level phosphorylation (C) Signup and view all the answers

What compound is formed when ADP is phosphorylated using the energy from creatine phosphate?

ATP (B) Signup and view all the answers

What is the significance of the wavy bond (~) in high-energy compounds like ATP?

It represents a high-energy bond. (C) Signup and view all the answers

Which enzyme is responsible for cleaving the high-energy phosphate bond in creatine phosphate?

Creatine kinase (CK) (B) Signup and view all the answers

What must occur for the endergonic reaction C → D to take place?

It must be coupled to exergonic reactions. (B) Signup and view all the answers

What is the primary role of the malate-aspartate shuttle system?

To facilitate transamination between oxaloacetate and glutamate (C) Signup and view all the answers

Which electron carrier is primarily used in the malate-aspartate shuttle?

NAD (C) Signup and view all the answers

Under what condition does the cell primarily enter state 3 or 5 during exercise?

Capacity of the respiratory chain when substrates are saturated (C) Signup and view all the answers

What happens to oxaloacetate in the malate-aspartate shuttle?

It carries electrons and protons into the mitochondrial matrix (C) Signup and view all the answers

What substance is generated when malate gives off electrons and protons in the matrix?

Oxaloacetate (D) Signup and view all the answers

Which state is associated with the availability of ADP only?

State 4 (B) Signup and view all the answers

Which shuttle system works alongside the creatine phosphate shuttle?

Malate-aspartate shuttle (A) Signup and view all the answers

What is the maximum yield of ATP produced through the malate-aspartate shuttle?

2.5 moles (B) Signup and view all the answers

What happens to molecular motion when solid water reaches absolute zero?

All molecular motion stops completely. (D) Signup and view all the answers

Which statement best describes the first law of thermodynamics?

Energy cannot be created nor destroyed, only transformed. (D) Signup and view all the answers

What does the symbol ΔG represent in thermodynamics?

Change in free energy. (C) Signup and view all the answers

In the equation ΔG = ΔH – TΔS, what does T represent?

The absolute temperature. (D) Signup and view all the answers

What is entropy in a thermodynamic context?

The measure of randomness in a system. (C) Signup and view all the answers

Why does burning a log not create energy or destroy matter?

Energy and matter merely change form. (D) Signup and view all the answers

Which of the following is NOT a type of energy mentioned in the context of thermodynamics?

Stored energy. (A) Signup and view all the answers

In the expression ΔG = ΔE - TΔS, what does ΔE represent?

Change in internal energy of the system. (D) Signup and view all the answers

Study Notes

### Energy Production and Thermodynamics

Forming ATP from ADP and inorganic phosphate requires energy (+7.3kcal/mol).
Breaking down ATP releases energy (-7.3kcal/mol)

High-Energy Phosphate Compounds

Hydrolyzing high-energy phosphate compounds like creatine phosphate releases energy.
This energy release is used to synthesize ATP.

Substrate-Level Phosphorylation

The synthesis of ATP by directly transferring a phosphate group from a high-energy phosphate compound (like creatine phosphate) to ADP.
Does not use energy from electron transport chain

Oxidative Phosphorylation

The process of ATP formation driven by the energy released from electrons during substrate (food) oxidation.
Occurs in the mitochondria via the respiratory chain (ETC)

Chemiosmotic Coupling Theory

Explains how oxidative phosphorylation works
Energy from oxidation of components in the electron transport chain (ETC) is coupled to the translocation of protons across the inner mitochondrial membrane.
Protons re-enter the matrix through ATP synthase (Complex V), generating ATP.

Electron Transport Chain

NADH and FADH2, produced during glycolysis, beta-oxidation, and the TCA cycle, carry electrons.
Electrons are transferred in stages through large protein complexes in the inner mitochondrial membrane.
Complexes I, III, and IV use energy from electron transfer to pump protons into the intermembrane space (IMS).
Complex II does not pump protons
The transfer of electrons from NADH to O2 creates an electrochemical potential (proton-motive force)

Malate-Aspartate Shuttle System

Used by the liver and heart cells
Transamination between oxaloacetate and glutamate
Uses NAD as a mitochondrial electron carrier, yielding 2.5 moles of ATP.

Laws of Thermodynamics

First Law: Energy is conserved. It can change forms but is not created or destroyed.
Second Law: Entropy (randomness) in a system always increases.

Thermodynamics Concepts

Enthalpy (H): Heat in a system
Entropy (S): Randomness in a system
Free energy (G): Energy available to do work.

Free Energy Change (ΔG)

Explains the relationship between the change in free energy (ΔG) and the change in entropy (ΔS)
Combines the first and second laws of thermodynamics.
Formula: ΔG = ΔH - TΔS
ΔH: Change in enthalpy
T: Absolute temperature

Exergonic and Endergonic Reactions

Exergonic: Reactions that release energy and have a negative ΔG.
Endergonic: Reactions that require energy and have a positive ΔG.

Coupling Reactions

Coupling an exergonic reaction to an endergonic reaction allows the endergonic reaction to proceed by trapping the released energy in a high-energy compound like ATP.
Only a portion of the released energy is used to drive the endergonic reaction, while the rest is released as heat.

Availability of ADP and Substrate

State 1: Limited by the availability of ADP and substrate.
State 2: Limited by substrate availability.
State 3: Limited by the capacity of the ETC.
State 4: Limited by ADP availability.
State 5: Limited by oxygen availability.
During exercise, cells approach states 3 or 5.

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Description

This quiz covers key concepts in biochemistry related to energy production, including the formation and breakdown of ATP, and the mechanisms of substrate-level and oxidative phosphorylation. Test your understanding of how energy is transferred and utilized within biological systems.