To indicate whether lactate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation. Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5 − phosphate , and other sugar phosphates are produced from glucose 6 − phosphate . Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle. Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes. Fermentation is defined as the biochemical anaerobic process by which NADH is oxidized to NAD + . In the lactate fermentation, NADH is oxidized to NAD + . The structure of lactate is as follows:

Question

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Answer 1

Question

Chapter 13, Problem 13.105EP

(a)

Interpretation Introduction

Interpretation: To indicate whether lactate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Fermentation is defined as the biochemical anaerobic process by which NADH is oxidized to NAD+. In the lactate fermentation, NADH is oxidized to NAD+.

The structure of lactate is as follows:

(a)

Expert Solution

Answer to Problem 13.105EP

Lactate is associated with (2) the Cori cycle and (4) the lactate fermentation.

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 2

Lactate is converted to pyruvate in the liver. Therefore, lactate is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

Therefore, lactate is associated with the Cori cycle and the lactate fermentation.

(b)

Interpretation Introduction

Interpretation: To indicate whether NAD+ is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

Nicotinamide adenine dinucleotide is associated with the redox reactions in metabolism. Its reduced form is NADH and oxidized form is NAD+.

(b)

Expert Solution

Answer to Problem 13.105EP

NAD+ is associated with (2) the Cori cycle, (3) glycolysis, and (4) the lactate fermentation.

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 3

In the Cori cycle, NADH/NAD+ are associated with the conversion of pyruvate to lactate and vice-versa. Therefore, NAD+ is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

In the lactate fermentation, NADH is oxidized to NAD+. Therefore, NAD+ is associated with the lactate fermentation.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

NAD+ are encountered as reactant in the glycolysis process. Therefore, NAD+ is involved in glycolysis.

(c)

Interpretation Introduction

Interpretation: To indicate whether glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

(c)

Expert Solution

Answer to Problem 13.105EP

Glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle and (3) glycolysis.

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The general equation for the entire pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Therefore, glucose 6−phosphate is encountered as the reactant in the Cori cycle.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

Glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. In the Cori cycle, glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. Therefore, glucose 6−phosphate is involved in the pentose phosphate pathway, the Cori cycle and glycolysis.

(d)

Interpretation Introduction

Interpretation: To indicate whether ribose 5−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate. The overall net equation for the pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

(d)

Expert Solution

Answer to Problem 13.105EP

Ribose 5−phosphate is involved in (1) the pentose phosphate pathway.

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The first step of the second stage i.e. the non-oxidative stage of the pentose phosphate pathway is the isomerization of ribulose 5−phosphate to ribose 5−phosphate. The isomerization equation for the first step of the second stage is as follows:

Ribulose 5−phosphate→Phosphopentose isomeraseRibose 5−phosphate

Ribose 5−phosphate is a pentose ribose that is formed in the first step of the second stage. Therefore, ribose 5−phosphate is involved in the pentose phosphate pathway.

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Answer 2

Question

Chapter 13, Problem 13.105EP

(a)

Interpretation Introduction

Interpretation: To indicate whether lactate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Fermentation is defined as the biochemical anaerobic process by which NADH is oxidized to NAD+. In the lactate fermentation, NADH is oxidized to NAD+.

The structure of lactate is as follows:

(a)

Expert Solution

Answer to Problem 13.105EP

Lactate is associated with (2) the Cori cycle and (4) the lactate fermentation.

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 2

Lactate is converted to pyruvate in the liver. Therefore, lactate is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

Therefore, lactate is associated with the Cori cycle and the lactate fermentation.

(b)

Interpretation Introduction

Interpretation: To indicate whether NAD+ is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

Nicotinamide adenine dinucleotide is associated with the redox reactions in metabolism. Its reduced form is NADH and oxidized form is NAD+.

(b)

Expert Solution

Answer to Problem 13.105EP

NAD+ is associated with (2) the Cori cycle, (3) glycolysis, and (4) the lactate fermentation.

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 3

In the Cori cycle, NADH/NAD+ are associated with the conversion of pyruvate to lactate and vice-versa. Therefore, NAD+ is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

In the lactate fermentation, NADH is oxidized to NAD+. Therefore, NAD+ is associated with the lactate fermentation.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

NAD+ are encountered as reactant in the glycolysis process. Therefore, NAD+ is involved in glycolysis.

(c)

Interpretation Introduction

Interpretation: To indicate whether glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

(c)

Expert Solution

Answer to Problem 13.105EP

Glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle and (3) glycolysis.

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The general equation for the entire pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Therefore, glucose 6−phosphate is encountered as the reactant in the Cori cycle.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

Glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. In the Cori cycle, glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. Therefore, glucose 6−phosphate is involved in the pentose phosphate pathway, the Cori cycle and glycolysis.

(d)

Interpretation Introduction

Interpretation: To indicate whether ribose 5−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate. The overall net equation for the pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

(d)

Expert Solution

Answer to Problem 13.105EP

Ribose 5−phosphate is involved in (1) the pentose phosphate pathway.

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The first step of the second stage i.e. the non-oxidative stage of the pentose phosphate pathway is the isomerization of ribulose 5−phosphate to ribose 5−phosphate. The isomerization equation for the first step of the second stage is as follows:

Ribulose 5−phosphate→Phosphopentose isomeraseRibose 5−phosphate

Ribose 5−phosphate is a pentose ribose that is formed in the first step of the second stage. Therefore, ribose 5−phosphate is involved in the pentose phosphate pathway.

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Answer 3

Question

Chapter 13, Problem 13.105EP

(a)

Interpretation Introduction

Interpretation: To indicate whether lactate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Fermentation is defined as the biochemical anaerobic process by which NADH is oxidized to NAD+. In the lactate fermentation, NADH is oxidized to NAD+.

The structure of lactate is as follows:

(a)

Expert Solution

Answer to Problem 13.105EP

Lactate is associated with (2) the Cori cycle and (4) the lactate fermentation.

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 2

Lactate is converted to pyruvate in the liver. Therefore, lactate is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

Therefore, lactate is associated with the Cori cycle and the lactate fermentation.

(b)

Interpretation Introduction

Interpretation: To indicate whether NAD+ is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

Nicotinamide adenine dinucleotide is associated with the redox reactions in metabolism. Its reduced form is NADH and oxidized form is NAD+.

(b)

Expert Solution

Answer to Problem 13.105EP

NAD+ is associated with (2) the Cori cycle, (3) glycolysis, and (4) the lactate fermentation.

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 3

In the Cori cycle, NADH/NAD+ are associated with the conversion of pyruvate to lactate and vice-versa. Therefore, NAD+ is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

In the lactate fermentation, NADH is oxidized to NAD+. Therefore, NAD+ is associated with the lactate fermentation.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

NAD+ are encountered as reactant in the glycolysis process. Therefore, NAD+ is involved in glycolysis.

(c)

Interpretation Introduction

Interpretation: To indicate whether glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

(c)

Expert Solution

Answer to Problem 13.105EP

Glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle and (3) glycolysis.

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The general equation for the entire pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Therefore, glucose 6−phosphate is encountered as the reactant in the Cori cycle.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

Glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. In the Cori cycle, glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. Therefore, glucose 6−phosphate is involved in the pentose phosphate pathway, the Cori cycle and glycolysis.

(d)

Interpretation Introduction

Interpretation: To indicate whether ribose 5−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate. The overall net equation for the pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

(d)

Expert Solution

Answer to Problem 13.105EP

Ribose 5−phosphate is involved in (1) the pentose phosphate pathway.

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The first step of the second stage i.e. the non-oxidative stage of the pentose phosphate pathway is the isomerization of ribulose 5−phosphate to ribose 5−phosphate. The isomerization equation for the first step of the second stage is as follows:

Ribulose 5−phosphate→Phosphopentose isomeraseRibose 5−phosphate

Ribose 5−phosphate is a pentose ribose that is formed in the first step of the second stage. Therefore, ribose 5−phosphate is involved in the pentose phosphate pathway.

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Answer 4

Question

Chapter 13, Problem 13.105EP

(a)

Interpretation Introduction

Interpretation: To indicate whether lactate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Fermentation is defined as the biochemical anaerobic process by which NADH is oxidized to NAD+. In the lactate fermentation, NADH is oxidized to NAD+.

The structure of lactate is as follows:

(a)

Expert Solution

Answer to Problem 13.105EP

Lactate is associated with (2) the Cori cycle and (4) the lactate fermentation.

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 2

Lactate is converted to pyruvate in the liver. Therefore, lactate is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

Therefore, lactate is associated with the Cori cycle and the lactate fermentation.

(b)

Interpretation Introduction

Interpretation: To indicate whether NAD+ is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

Nicotinamide adenine dinucleotide is associated with the redox reactions in metabolism. Its reduced form is NADH and oxidized form is NAD+.

(b)

Expert Solution

Answer to Problem 13.105EP

NAD+ is associated with (2) the Cori cycle, (3) glycolysis, and (4) the lactate fermentation.

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 3

In the Cori cycle, NADH/NAD+ are associated with the conversion of pyruvate to lactate and vice-versa. Therefore, NAD+ is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

In the lactate fermentation, NADH is oxidized to NAD+. Therefore, NAD+ is associated with the lactate fermentation.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

NAD+ are encountered as reactant in the glycolysis process. Therefore, NAD+ is involved in glycolysis.

(c)

Interpretation Introduction

Interpretation: To indicate whether glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

(c)

Expert Solution

Answer to Problem 13.105EP

Glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle and (3) glycolysis.

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The general equation for the entire pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Therefore, glucose 6−phosphate is encountered as the reactant in the Cori cycle.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

Glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. In the Cori cycle, glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. Therefore, glucose 6−phosphate is involved in the pentose phosphate pathway, the Cori cycle and glycolysis.

(d)

Interpretation Introduction

Interpretation: To indicate whether ribose 5−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate. The overall net equation for the pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

(d)

Expert Solution

Answer to Problem 13.105EP

Ribose 5−phosphate is involved in (1) the pentose phosphate pathway.

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The first step of the second stage i.e. the non-oxidative stage of the pentose phosphate pathway is the isomerization of ribulose 5−phosphate to ribose 5−phosphate. The isomerization equation for the first step of the second stage is as follows:

Ribulose 5−phosphate→Phosphopentose isomeraseRibose 5−phosphate

Ribose 5−phosphate is a pentose ribose that is formed in the first step of the second stage. Therefore, ribose 5−phosphate is involved in the pentose phosphate pathway.

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Answer 5

Chapter 13, Problem 13.105EP

(a)

Interpretation Introduction

Interpretation: To indicate whether lactate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Fermentation is defined as the biochemical anaerobic process by which NADH is oxidized to NAD+. In the lactate fermentation, NADH is oxidized to NAD+.

The structure of lactate is as follows:

(a)

Expert Solution

Answer to Problem 13.105EP

Lactate is associated with (2) the Cori cycle and (4) the lactate fermentation.

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 2

Lactate is converted to pyruvate in the liver. Therefore, lactate is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

Therefore, lactate is associated with the Cori cycle and the lactate fermentation.

(b)

Interpretation Introduction

Interpretation: To indicate whether NAD+ is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

Nicotinamide adenine dinucleotide is associated with the redox reactions in metabolism. Its reduced form is NADH and oxidized form is NAD+.

(b)

Expert Solution

Answer to Problem 13.105EP

NAD+ is associated with (2) the Cori cycle, (3) glycolysis, and (4) the lactate fermentation.

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 3

In the Cori cycle, NADH/NAD+ are associated with the conversion of pyruvate to lactate and vice-versa. Therefore, NAD+ is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

In the lactate fermentation, NADH is oxidized to NAD+. Therefore, NAD+ is associated with the lactate fermentation.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

NAD+ are encountered as reactant in the glycolysis process. Therefore, NAD+ is involved in glycolysis.

(c)

Interpretation Introduction

Interpretation: To indicate whether glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

(c)

Expert Solution

Answer to Problem 13.105EP

Glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle and (3) glycolysis.

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The general equation for the entire pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Therefore, glucose 6−phosphate is encountered as the reactant in the Cori cycle.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

Glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. In the Cori cycle, glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. Therefore, glucose 6−phosphate is involved in the pentose phosphate pathway, the Cori cycle and glycolysis.

(d)

Interpretation Introduction

Interpretation: To indicate whether ribose 5−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate. The overall net equation for the pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

(d)

Expert Solution

Answer to Problem 13.105EP

Ribose 5−phosphate is involved in (1) the pentose phosphate pathway.

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The first step of the second stage i.e. the non-oxidative stage of the pentose phosphate pathway is the isomerization of ribulose 5−phosphate to ribose 5−phosphate. The isomerization equation for the first step of the second stage is as follows:

Ribulose 5−phosphate→Phosphopentose isomeraseRibose 5−phosphate

Ribose 5−phosphate is a pentose ribose that is formed in the first step of the second stage. Therefore, ribose 5−phosphate is involved in the pentose phosphate pathway.

Answer 6

Chapter 13, Problem 13.105EP

(a)

Interpretation Introduction

Interpretation: To indicate whether lactate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Fermentation is defined as the biochemical anaerobic process by which NADH is oxidized to NAD+. In the lactate fermentation, NADH is oxidized to NAD+.

The structure of lactate is as follows:

(a)

Expert Solution

Answer to Problem 13.105EP

Lactate is associated with (2) the Cori cycle and (4) the lactate fermentation.

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 2

Lactate is converted to pyruvate in the liver. Therefore, lactate is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

Therefore, lactate is associated with the Cori cycle and the lactate fermentation.

Answer 7

Chapter 13, Problem 13.105EP

(a)

Interpretation Introduction

Interpretation: To indicate whether lactate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Fermentation is defined as the biochemical anaerobic process by which NADH is oxidized to NAD+. In the lactate fermentation, NADH is oxidized to NAD+.

The structure of lactate is as follows:

Answer 8

(a)

Expert Solution

Answer to Problem 13.105EP

Lactate is associated with (2) the Cori cycle and (4) the lactate fermentation.

Answer 9

(a)

Expert Solution

Answer 10

(a)

Expert Solution

Answer 11

Expert Solution

Answer 12

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 2

Lactate is converted to pyruvate in the liver. Therefore, lactate is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

Therefore, lactate is associated with the Cori cycle and the lactate fermentation.

Answer 13

(b)

Interpretation Introduction

Interpretation: To indicate whether NAD+ is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

Nicotinamide adenine dinucleotide is associated with the redox reactions in metabolism. Its reduced form is NADH and oxidized form is NAD+.

(b)

Expert Solution

Answer to Problem 13.105EP

NAD+ is associated with (2) the Cori cycle, (3) glycolysis, and (4) the lactate fermentation.

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 3

In the Cori cycle, NADH/NAD+ are associated with the conversion of pyruvate to lactate and vice-versa. Therefore, NAD+ is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

In the lactate fermentation, NADH is oxidized to NAD+. Therefore, NAD+ is associated with the lactate fermentation.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

NAD+ are encountered as reactant in the glycolysis process. Therefore, NAD+ is involved in glycolysis.

Answer 14

(b)

Interpretation Introduction

Interpretation: To indicate whether NAD+ is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

Nicotinamide adenine dinucleotide is associated with the redox reactions in metabolism. Its reduced form is NADH and oxidized form is NAD+.

Answer 15

(b)

Expert Solution

Answer to Problem 13.105EP

NAD+ is associated with (2) the Cori cycle, (3) glycolysis, and (4) the lactate fermentation.

Answer 16

(b)

Expert Solution

Answer 17

(b)

Expert Solution

Answer 18

Expert Solution

Answer 19

Explanation of Solution

An overview of the Cori cycle is as follows:

Organic And Biological Chemistry, Chapter 13, Problem 13.105EP , additional homework tip 3

In the Cori cycle, NADH/NAD+ are associated with the conversion of pyruvate to lactate and vice-versa. Therefore, NAD+ is associated with the Cori cycle.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation. The chemical reaction for the formation of lactate is as follows:

Pyruvate+NADH+H+→Lactatedehydrogenaselactate+NAD+

In the lactate fermentation, NADH is oxidized to NAD+. Therefore, NAD+ is associated with the lactate fermentation.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

NAD+ are encountered as reactant in the glycolysis process. Therefore, NAD+ is involved in glycolysis.

Answer 20

(c)

Interpretation Introduction

Interpretation: To indicate whether glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

(c)

Expert Solution

Answer to Problem 13.105EP

Glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle and (3) glycolysis.

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The general equation for the entire pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Therefore, glucose 6−phosphate is encountered as the reactant in the Cori cycle.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

Glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. In the Cori cycle, glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. Therefore, glucose 6−phosphate is involved in the pentose phosphate pathway, the Cori cycle and glycolysis.

Answer 21

(c)

Interpretation Introduction

Interpretation: To indicate whether glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate.

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

Answer 22

(c)

Expert Solution

Answer to Problem 13.105EP

Glucose 6−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle and (3) glycolysis.

Answer 23

(c)

Expert Solution

Answer 24

(c)

Expert Solution

Answer 25

Expert Solution

Answer 26

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The general equation for the entire pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Therefore, glucose 6−phosphate is encountered as the reactant in the Cori cycle.

The net overall equation for the glycolysis process is as follows:

Glucose+2ADP+2Pi+2NAD+→2pyruvate+2NADH+2ATP+2H++2H2O

Glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. In the Cori cycle, glucose enters the glycolysis metabolic pathway in the form of glucose 6−phosphate. Therefore, glucose 6−phosphate is involved in the pentose phosphate pathway, the Cori cycle and glycolysis.

Answer 27

(d)

Interpretation Introduction

Interpretation: To indicate whether ribose 5−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate. The overall net equation for the pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

(d)

Expert Solution

Answer to Problem 13.105EP

Ribose 5−phosphate is involved in (1) the pentose phosphate pathway.

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The first step of the second stage i.e. the non-oxidative stage of the pentose phosphate pathway is the isomerization of ribulose 5−phosphate to ribose 5−phosphate. The isomerization equation for the first step of the second stage is as follows:

Ribulose 5−phosphate→Phosphopentose isomeraseRibose 5−phosphate

Ribose 5−phosphate is a pentose ribose that is formed in the first step of the second stage. Therefore, ribose 5−phosphate is involved in the pentose phosphate pathway.

Answer 28

(d)

Interpretation Introduction

Interpretation: To indicate whether ribose 5−phosphate is involved in (1) the pentose phosphate pathway, (2) the Cori cycle, (3) glycolysis, or (4) lactate fermentation.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, ribose 5−phosphate, and other sugar phosphates are produced from glucose 6−phosphate. The overall net equation for the pentose phosphate pathway is as follows:

3Glucose 6−phosphate+6NADP++3H2O→2fructose 6−phosphate+6NADPH+3CO2+6H++glyceraldehyde 3−phosphate

Glucose is converted to pyruvate by glycolysis metabolic pathway; pyruvate is further converted to lactate in the skeletal muscle cells by anaerobic reactions. The lactate is diffused into the bloodstream, by which it is transported to the liver. Lactate is reconverted to pyruvate. Gluconeogenesis metabolic pathway uses this pyruvate to synthesize glucose in the liver cells. Glucose is diffused into the bloodstream and is transported back to the active skeletal muscle cells. This cycle is known as the Cori cycle.

Glycolysis is the metabolic pathway that breaks down a glucose molecule and converts it into two pyruvate molecules along with the production of two ATP molecules and NADH coenzymes.

Pyruvate is converted to lactate under oxygen-poor conditions by lactate dehydrogenase enzymes in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.

Answer 29

(d)

Expert Solution

Answer to Problem 13.105EP

Ribose 5−phosphate is involved in (1) the pentose phosphate pathway.

Answer 30

(d)

Expert Solution

Answer 31

(d)

Expert Solution

Answer 32

Expert Solution

Answer 33

Explanation of Solution

The first stage of the pentose phosphate pathway is the oxidative stage. In the oxidative stage (involves three steps) of the pentose phosphate pathway, glucose 6−phosphate is converted to ribulose 5−phosphate and CO2. NADPH is formed along with ribulose 5−phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6−phosphate+2NADP++H2O→ribulose 5−phosphate+2NADPH+CO2+2H+

The first step of the second stage i.e. the non-oxidative stage of the pentose phosphate pathway is the isomerization of ribulose 5−phosphate to ribose 5−phosphate. The isomerization equation for the first step of the second stage is as follows:

Ribulose 5−phosphate→Phosphopentose isomeraseRibose 5−phosphate

Ribose 5−phosphate is a pentose ribose that is formed in the first step of the second stage. Therefore, ribose 5−phosphate is involved in the pentose phosphate pathway.