Chapter 24, Problem 31P

Interpretation Introduction

(a)

Interpretation:

The step of glycolysis in which ATP are formed 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:

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

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 31P

In glycolysis, ATP's are formed in step-7 and 10.

Explanation of Solution

The metabolism of glucose starts from the glycolysis process. It is the first step in cellular metabolism to extract energy from glucose. It is the sequence of 10 enzyme-catalyzed reactions that involve the conversion of glucose molecules into pyruvate with the production of ATP molecules.

The overall reaction of glycolysis must be written as:

  ${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}{\text{ + 2 NAD}}^{\text{+}}\text{ + 2 ADP + 2 P }\stackrel{}{\to }{\text{ 2 (CH}}_{\text{3}}\left(\text{C=O}\right){\text{COOH + 2 ATP + 2 NADH + 2 H}}^{\text{+}}$

Two steps; 7^th and 10^th step are involved in the production of ATP;

• Conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate occurs with the conversion of ADP to form ATP in the presence of Phosphoglycerate kinase that transfers a phosphate group.
• Conversion of phosphoenolpyruvate (PEP) to pyruvic acid with the conversion of ATP in the presence enzyme pyruvate kinase

Interpretation Introduction

(b)

Interpretation:

The step of glycolysis which uses ATP molecules 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:

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

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 31P

In glycolysis, ATP's are formed in step-1 and 3.

Explanation of Solution

The metabolism of glucose starts from the glycolysis process. It is the first step in cellular metabolism to extract energy from glucose. It is the sequence of 10 enzyme-catalyzed reactions that involves the conversion of glucose molecules into pyruvate with the production of ATP molecules.

The overall reaction of glycolysis must be written as:

  ${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}{\text{ + 2 NAD}}^{\text{+}}\text{ + 2 ADP + 2 P }\stackrel{}{\to }{\text{ 2 (CH}}_{\text{3}}\left(\text{C=O}\right){\text{COOH + 2 ATP + 2 NADH + 2 H}}^{\text{+}}$

Two steps; 1^st and 3^rdstep use ATP molecules.

• The first step in glycolysis, glucose converts to glucose-6-phosphate in the presence of hexokinase. It uses energy in the form of ATP and converts it to ADP molecule.

 

• Phosphofructokinase, with magnesium as a cofactor, changes fructose 6-phosphate into fructose 1, 6-bisphosphate.

 

Interpretation Introduction

(c)

Interpretation:

The step of glycolysis which forms a reduce coenzyme 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:

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

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 31P

In glycolysis, step-6 forms a reduced coenzyme NADH.

Explanation of Solution

The metabolism of glucose starts from the glycolysis process. It is the first step in cellular metabolism to extract energy from glucose. It is the sequence of 10 enzyme-catalyzed reactions which involves the conversion of glucose molecules into pyruvate with the production of ATP molecules.

The overall reaction of glycolysis must be written as:

  ${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}{\text{ + 2 NAD}}^{\text{+}}\text{ + 2 ADP + 2 P }\stackrel{}{\to }{\text{ 2 (CH}}_{\text{3}}\left(\text{C=O}\right){\text{COOH + 2 ATP + 2 NADH + 2 H}}^{\text{+}}$

In the 6^th step of glycolysis, glyceraldehyde-3-phosphate converts to 1,3-bisphosphoglycerate. It is a dehydrogenation step that occurs in the presence of Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and converts NAD+ to NADH and H+ ⁱons.

 

Interpretation Introduction

(c)

Interpretation:

The step of glycolysis which breaks a C-C bond 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 31P

In glycolysis, step-4breaks a C-C bond.

Explanation of Solution

The metabolism of glucose starts from the glycolysis process. It is the first step in cellular metabolism to extract energy from glucose. It is the sequence of 10 enzyme-catalyzed reactions which involves the conversion of glucose molecules into pyruvate with production of ATP molecules.

The overall reaction of glycolysis must be written as:

  ${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}{\text{ + 2 NAD}}^{\text{+}}\text{ + 2 ADP + 2 P }\stackrel{}{\to }{\text{ 2 (CH}}_{\text{3}}\left(\text{C=O}\right){\text{COOH + 2 ATP + 2 NADH + 2 H}}^{\text{+}}$

In the 4^thstep of glycolysis, in the presence of enzyme Aldolase, fructose 1, 6-bisphosphate breaks into two sugar molecules. These sugar molecules are isomers of each other; dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP).