Chapter 23, Problem 53P

What is the role of each of the following in the electron transport chain: (a) ${\text{FADH}}_{\text{2}};$ (b) ADP; (c) ATP synthase; (d) the inner mitochondrial membrane?

Interpretation Introduction

(a)

Interpretation:

The role of FADH₂ in the electron transport chain should be determined.

Concept Introduction:

Aerobic respiration occurs in two steps:

• Glycolysis
• Citric acid cycle

Glycolysis is the first step that forms pyruvate as given below:

  ${\text{Glucose + 2ATP + 2NAD}}^{\text{+}}{\text{ + 4ADP + 2P}}_{\text{i}}\stackrel{}{\to }{\text{ 2 Pyruvate + 4ATP + 2NADH + 2H}}^{\text{+}}$

In the presence of oxygen means aerobic respiration, this pyruvate enters in the Krebs cycle and extracts energy in the form of electrons transfer. Electrons are transferred from the pyruvate to the receptors like ${\text{NAD}}^{\text{+}}{\text{, GDP, and FAD and CO}}_{\text{2}}$ gas is formed as the waste product. The products of citric acid cycles act as precursors for electron transport chains.

Answer to Problem 53P

FADH₂ is created from FAD through reduction-oxidation reactions in the Krebs cycle during respiration. It gives its electrons in the electron transport chain that produces two ATPs for every FADH₂ molecule.

Explanation of Solution

Citric acid cycle is also known as the tricarboxylic acid cycle or Krebs cycles. In this cycle, all intermediates are carboxylate anions mainly which are formed from di or tricarboxylic acid during the reaction. It initiates with the reaction of acetyl CoA (a 2 C's substance) that reacts with a 4 C's substance to form a product of 6 C's. Later, carbon atoms are removed in the form of carbon dioxide gas.

In this process, 2 H's are transferred to FAD and produce FADH₂. This energy carrier remains attached to the enzyme and transfers the electrons to the electron transport chain. The electron transport chain is a series of four enzyme complexes and two coenzymes:

• Complex I to Complex IV
• Coenzymes -ubiquinone and Cytochrome c

FADH₂ is created from FAD through reduction-oxidation reactions in the Krebs cycle during respiration. It gives its electrons in the electron transport chain that produces two ATPs for every FADH₂ molecule.

Interpretation Introduction

(b)

Interpretation:

The role of ADP in the electron transport chain should be determined.

Concept Introduction:

Aerobic respiration occurs in two steps:

• Glycolysis
• Citric acid cycle

Glycolysis is the first step that forms pyruvate as given below:

  ${\text{Glucose + 2ATP + 2NAD}}^{\text{+}}{\text{ + 4ADP + 2P}}_{\text{i}}\stackrel{}{\to }{\text{ 2 Pyruvate + 4ATP + 2NADH + 2H}}^{\text{+}}$

In the presence of oxygen means aerobic respiration, this pyruvate enters the Krebs cycle and extracts energy in the form of electrons transfer. Electrons are transferred from the pyruvate to the receptors like ${\text{NAD}}^{\text{+}}{\text{, GDP, and FAD and CO}}_{\text{2}}$ gas is formed as the waste product. The products of citric acid cycles act as precursors for electron transport chains.

Answer to Problem 53P

In the electron transport chain, a single molecule of NADH has generated three ATP molecules from ADP in the mitochondria.

Explanation of Solution

Citric acid cycle is also known as the tricarboxylic acid cycle or Krebs cycles. In this cycle, all intermediates are carboxylate anions mainly which are formed from di or tricarboxylic acid during the reaction.

In this process, 2 H's are transferred to FAD and produce FADH₂. This energy carrier remains attached to the enzyme and transfers the electrons to the electron transport chain. The electron transport chain is a series of four enzyme complexes and two coenzymes:

• Complex I to Complex IV
• Coenzymes -ubiquinone and Cytochrome c

In the electron transport chain, a single molecule of NADH has generated three ATP molecules from ADP in the mitochondria.

Interpretation Introduction

(c)

Interpretation:

The role of ATP synthase in the electron transport chain should be determined.

Concept Introduction:

Aerobic respiration occurs in two steps:

• Glycolysis
• Citric acid cycle

Glycolysis is the first step that forms pyruvate as given below:

  ${\text{Glucose + 2ATP + 2NAD}}^{\text{+}}{\text{ + 4ADP + 2P}}_{\text{i}}\stackrel{}{\to }{\text{ 2 Pyruvate + 4ATP + 2NADH + 2H}}^{\text{+}}$

In the presence of oxygen means aerobic respiration, this pyruvate enters the Krebs cycle and extracts energy in the form of electrons transfer. Electrons are transferred from the pyruvate to the receptors like ${\text{NAD}}^{\text{+}}{\text{, GDP, and FAD and CO}}_{\text{2}}$ gas is formed as the waste product. The products of citric acid cycles act as precursors for electron transport chains.

Answer to Problem 53P

In the electron transport chain, the ATP synthase is an enzyme that converts the mechanical work into chemical energy and produces an ATP molecule. The ATP powers most cellular reactions in the living organism.

Explanation of Solution

Citric acid cycle is also known as the tricarboxylic acid cycle or Krebs cycles. In this cycle, all intermediates are carboxylate anions mainly which are formed from di or tricarboxylic acid during the reaction.

In this process, 2 H's are transferred to FAD and produce FADH₂. This energy carrier remains attached to the enzyme and transfers the electrons to the electron transport chain. The electron transport chain is a series of four enzyme complexes and two coenzymes:

• Complex I to Complex IV
• Coenzymes -ubiquinone and Cytochrome c

In the electron transport chain, the ATP synthase is an enzyme that converts the mechanical work into chemical energy and produces an ATP molecule. The ATP powers most cellular reactions in the living organism.

Interpretation Introduction

(d)

Interpretation:

The role of the inner mitochondrial membrane in the electron transport chain should be determined.

Concept Introduction:

Aerobic respiration occurs in two steps:

• Glycolysis
• Citric acid cycle

Glycolysis is the first step that forms pyruvate as given below:

  ${\text{Glucose + 2ATP + 2NAD}}^{\text{+}}{\text{ + 4ADP + 2P}}_{\text{i}}\stackrel{}{\to }{\text{ 2 Pyruvate + 4ATP + 2NADH + 2H}}^{\text{+}}$

In the presence of oxygen means aerobic respiration, this pyruvate enters the Krebs cycle and extracts energy in the form of electrons transfer. Electrons are transferred from the pyruvate to the receptors like ${\text{NAD}}^{\text{+}}{\text{, GDP, and FAD and CO}}_{\text{2}}$ gas is formed as the waste product. The products of citric acid cycles act as precursors for electron transport chains.

Answer to Problem 53P

The electron transport chain is embedded in the inner mitochondrial membrane and it involves the shuffles in the electrons from NADH and FADH₂ to molecular oxygen.

Explanation of Solution

Citric acid cycle is also known as the tricarboxylic acid cycle or Krebs cycles. In this cycle, all intermediates are carboxylate anions mainly which are formed from di or tricarboxylic acid during the reaction.

In this process, 2 H's are transferred to FAD and produces FADH₂. This energy carrier remains attached to the enzyme and transfers the electrons to the electron transport chain. The electron transport chain is a series of four enzyme complexes and two coenzymes:

• Complex I to Complex IV
• Coenzymes -ubiquinone and Cytochrome c

The electron transport chain is embedded in the inner mitochondrial membrane and it involves the shuffles in the electrons from NADH and FADH₂ to molecular oxygen.

The electron transport chain process is involved in the pumping of the protons from the mitochondrial matrix to the intermembrane space. It reduces oxygen and forms water.