General, Organic, and Biological Chemistry
General, Organic, and Biological Chemistry
7th Edition
ISBN: 9781285853918
Author: H. Stephen Stoker
Publisher: Cengage Learning
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Chapter 24, Problem 24.105EP

(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 5phosphate, and other sugar phosphates are produced from glucose 6phosphate.

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:

General, Organic, and Biological Chemistry, Chapter 24, Problem 24.105EP , additional homework tip  1

(a)

Expert Solution
Check Mark

Answer to Problem 24.105EP

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:

General, Organic, and Biological Chemistry, Chapter 24, Problem 24.105EP , 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 5phosphate, and other sugar phosphates are produced from glucose 6phosphate.

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
Check Mark

Answer to Problem 24.105EP

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:

General, Organic, and Biological Chemistry, Chapter 24, Problem 24.105EP , 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 6phosphate 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 5phosphate, and other sugar phosphates are produced from glucose 6phosphate.

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
Check Mark

Answer to Problem 24.105EP

Glucose 6phosphate 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 6phosphate is converted to ribulose 5phosphate and CO2. NADPH is formed along with ribulose 5phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6phosphate+2NADP++H2Oribulose 5phosphate+2NADPH+CO2+2H+

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

3Glucose 6phosphate+6NADP++3H2O2fructose 6phosphate+6NADPH+3CO2+6H++glyceraldehyde 3phosphate

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

(d)

Interpretation Introduction

Interpretation: To indicate whether ribose 5phosphate 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 5phosphate, and other sugar phosphates are produced from glucose 6phosphate. The overall net equation for the pentose phosphate pathway is as follows:

3Glucose 6phosphate+6NADP++3H2O2fructose 6phosphate+6NADPH+3CO2+6H++glyceraldehyde 3phosphate

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
Check Mark

Answer to Problem 24.105EP

Ribose 5phosphate 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 6phosphate is converted to ribulose 5phosphate and CO2. NADPH is formed along with ribulose 5phosphate and CO2. The net equation for the oxidative stage is as follows:

Glucose 6phosphate+2NADP++H2Oribulose 5phosphate+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 5phosphate to ribose 5phosphate. The isomerization equation for the first step of the second stage is as follows:

Ribulose 5phosphatePhosphopentose isomeraseRibose 5phosphate

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

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Chapter 24 Solutions

General, Organic, and Biological Chemistry

Ch. 24.2 - Prob. 6QQCh. 24.2 - Prob. 7QQCh. 24.3 - Prob. 1QQCh. 24.3 - Prob. 2QQCh. 24.3 - Prob. 3QQCh. 24.3 - Prob. 4QQCh. 24.3 - Accumulation of which of the following substances...Ch. 24.4 - Prob. 1QQCh. 24.4 - The net yield of ATP for the complete oxidation of...Ch. 24.4 - Prob. 3QQCh. 24.5 - Prob. 1QQCh. 24.5 - Prob. 2QQCh. 24.5 - Prob. 3QQCh. 24.6 - Prob. 1QQCh. 24.6 - Prob. 2QQCh. 24.6 - Prob. 3QQCh. 24.6 - Which of the following statements about ATP...Ch. 24.6 - Prob. 5QQCh. 24.7 - Prob. 1QQCh. 24.7 - Prob. 2QQCh. 24.8 - Prob. 1QQCh. 24.8 - Prob. 2QQCh. 24.8 - Prob. 3QQCh. 24.9 - Which of the following hormones promotes the...Ch. 24.9 - Which of the following pairs of hormones increases...Ch. 24.10 - Prob. 1QQCh. 24.10 - Prob. 2QQCh. 24.10 - Prob. 3QQCh. 24 - Where does carbohydrate digestion begin in the...Ch. 24 - Very little digestion of carbohydrates occurs in...Ch. 24 - Prob. 24.3EPCh. 24 - Prob. 24.4EPCh. 24 - Prob. 24.5EPCh. 24 - Prob. 24.6EPCh. 24 - Prob. 24.7EPCh. 24 - Prob. 24.8EPCh. 24 - Prob. 24.9EPCh. 24 - Prob. 24.10EPCh. 24 - Prob. 24.11EPCh. 24 - Prob. 24.12EPCh. 24 - Prob. 24.13EPCh. 24 - Prob. 24.14EPCh. 24 - Prob. 24.15EPCh. 24 - Prob. 24.16EPCh. 24 - Prob. 24.17EPCh. 24 - Prob. 24.18EPCh. 24 - Prob. 24.19EPCh. 24 - Prob. 24.20EPCh. 24 - Prob. 24.21EPCh. 24 - Prob. 24.22EPCh. 24 - Prob. 24.23EPCh. 24 - Prob. 24.24EPCh. 24 - Prob. 24.25EPCh. 24 - Prob. 24.26EPCh. 24 - Prob. 24.27EPCh. 24 - Prob. 24.28EPCh. 24 - Prob. 24.29EPCh. 24 - Prob. 24.30EPCh. 24 - Prob. 24.31EPCh. 24 - Prob. 24.32EPCh. 24 - Prob. 24.33EPCh. 24 - Prob. 24.34EPCh. 24 - Prob. 24.35EPCh. 24 - Prob. 24.36EPCh. 24 - Prob. 24.37EPCh. 24 - Prob. 24.38EPCh. 24 - Prob. 24.39EPCh. 24 - Prob. 24.40EPCh. 24 - Prob. 24.41EPCh. 24 - Prob. 24.42EPCh. 24 - Prob. 24.43EPCh. 24 - Prob. 24.44EPCh. 24 - Prob. 24.45EPCh. 24 - Prob. 24.46EPCh. 24 - Prob. 24.47EPCh. 24 - Prob. 24.48EPCh. 24 - Prob. 24.49EPCh. 24 - Prob. 24.50EPCh. 24 - Prob. 24.51EPCh. 24 - Prob. 24.52EPCh. 24 - Prob. 24.53EPCh. 24 - Prob. 24.54EPCh. 24 - Prob. 24.55EPCh. 24 - Prob. 24.56EPCh. 24 - Prob. 24.57EPCh. 24 - Prob. 24.58EPCh. 24 - Prob. 24.59EPCh. 24 - Prob. 24.60EPCh. 24 - Prob. 24.61EPCh. 24 - Prob. 24.62EPCh. 24 - Prob. 24.63EPCh. 24 - Prob. 24.64EPCh. 24 - Prob. 24.65EPCh. 24 - The liver, but not the brain or muscle cells, has...Ch. 24 - Prob. 24.67EPCh. 24 - Prob. 24.68EPCh. 24 - Prob. 24.69EPCh. 24 - Prob. 24.70EPCh. 24 - Prob. 24.71EPCh. 24 - Prob. 24.72EPCh. 24 - Prob. 24.73EPCh. 24 - Prob. 24.74EPCh. 24 - Prob. 24.75EPCh. 24 - Prob. 24.76EPCh. 24 - Prob. 24.77EPCh. 24 - Prob. 24.78EPCh. 24 - Prob. 24.79EPCh. 24 - Prob. 24.80EPCh. 24 - Prob. 24.81EPCh. 24 - Prob. 24.82EPCh. 24 - Prob. 24.83EPCh. 24 - Prob. 24.84EPCh. 24 - Prob. 24.85EPCh. 24 - Prob. 24.86EPCh. 24 - Prob. 24.87EPCh. 24 - Prob. 24.88EPCh. 24 - Prob. 24.89EPCh. 24 - Prob. 24.90EPCh. 24 - Prob. 24.91EPCh. 24 - Prob. 24.92EPCh. 24 - Prob. 24.93EPCh. 24 - Prob. 24.94EPCh. 24 - Prob. 24.95EPCh. 24 - Prob. 24.96EPCh. 24 - Prob. 24.97EPCh. 24 - Prob. 24.98EPCh. 24 - Prob. 24.99EPCh. 24 - Prob. 24.100EPCh. 24 - Prob. 24.101EPCh. 24 - Prob. 24.102EPCh. 24 - Prob. 24.103EPCh. 24 - Prob. 24.104EPCh. 24 - Prob. 24.105EPCh. 24 - Prob. 24.106EPCh. 24 - Prob. 24.107EPCh. 24 - Prob. 24.108EPCh. 24 - Prob. 24.109EPCh. 24 - Prob. 24.110EPCh. 24 - Prob. 24.111EPCh. 24 - Prob. 24.112EPCh. 24 - Prob. 24.113EPCh. 24 - Prob. 24.114EPCh. 24 - Prob. 24.115EPCh. 24 - Compare the biological functions of glucagon and...Ch. 24 - Prob. 24.117EPCh. 24 - Prob. 24.118EP
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