GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP
GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP
7th Edition
ISBN: 9781305866966
Author: STOKER
Publisher: CENGAGE L
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Chapter 23, Problem 23.70EP

(a)

Interpretation Introduction

Interpretation: To determine the number of NADH molecules formed during one turn of the citric acid cycle.

Concept introduction: Citric acid cycle is the third stage of the biochemical energy production process. The cycle includes the reactions in which the acetyl part of acetyl CoA is oxidized and leads to the formation of carbon dioxide and CoA-SH. An overview of the citric acid cycle is as follows:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  1

NADH is the reduced form of nicotinamide adenine dinucleotide. It is employed as an oxidizing agent in various reactions like oxidation of secondary alcohol into a ketone. Its structure consists of three subunits: nicotinamide, ribose, and ADP.

(a)

Expert Solution
Check Mark

Answer to Problem 23.70EP

Three molecules of NADH are formed in step 3, 4 and 8 of the citric acid cycle.

Explanation of Solution

Step 3 is the first step where both the oxidation and decarboxylation occurs. Step 3 involves the oxidation of isocitrate and formation of CO2. In this step, firstly isocitrate is oxidized by NAD+ to form oxalosuccinate and then decarboxylation takes place to form α-ketoglutarate. The reaction of this step is:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  2

NAD+ acts as an oxidizing agent in this step. Isocitrate is oxidized to oxalosuccinate and NAD+ is reduced to form NADH.

Step 4 involves the oxidation of α-ketoglutarate and formation of CO2. In this step, α-ketoglutarate is reacted with CoA-SH and NAD+. This is the second oxidation reaction of the citric acid cycle and leads to the formation of succinyl CoA. The enzyme employed for oxidation is α-ketoglutarate dehydrogenase. The reaction of step 4 is:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  3

NAD+ acts as an oxidizing agent in this step. α-ketoglutarate is oxidized to succinyl CoA and NAD+ is reduced to form NADH.

Step 8 is an oxidation reaction and the last step of the citric acid cycle. In step 8, L-malate is oxidized to regenerate oxaloacetate with the help of enzyme malate dehydrogenase. NAD+ acts as an oxidizing agent in the reaction.

The reaction of step 8 is:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  4

NAD+ acts as an oxidizing agent in this step. L-malate is oxidized to oxaloacetate and NAD+ is reduced to form NADH.

Hence, three molecules of NADH are formed in the citric acid cycle.

(b)

Interpretation Introduction

Interpretation: To determine the number of GTP molecules formed during one turn of the citric acid cycle.

Concept introduction: Citric acid cycle is the third stage of the biochemical energy production process. The cycle includes the reactions in which the acetyl part of acetyl CoA is oxidized and leads to the formation of carbon dioxide and CoA-SH. An overview of the citric acid cycle is as follows:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  5

(b)

Expert Solution
Check Mark

Answer to Problem 23.70EP

One molecule of GTP is formed in step 5 of the citric acid cycle.

Explanation of Solution

Step 5 involves the thioester bond cleavage in succinyl CoA and phosphorylation of GDP. This step consists of two reactions. Firstly succinyl CoA is converted into succinyl phosphate by the reaction with Pi and then succinyl phosphate is reacted with GDP to form succinate and GTP. The reaction of step 5 is:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  6

(c)

Interpretation Introduction

Interpretation: To determine the number of time decarboxylation reactions occur during one turn of the citric acid cycle.

Concept introduction: Citric acid cycle is the third stage of the biochemical energy production process. The cycle includes the reactions in which the acetyl part of acetyl CoA is oxidized and leads to the formation of carbon dioxide and CoA-SH. An overview of the citric acid cycle is as follows:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  7

(c)

Expert Solution
Check Mark

Answer to Problem 23.70EP

Decarboxylation occurs twice in the citric acid cycle in step 3 and 4.

Explanation of Solution

Step 3 is the first step where both the oxidation and decarboxylation occurs. Step 3 involves the oxidation of isocitrate and formation of CO2. In this step, firstly isocitrate is oxidized by NAD+ to form oxalosuccinate and then decarboxylation takes place to form α-ketoglutarate. The reaction of this step is:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  8

The final product is α-ketoglutarate and one molecule of CO2 is released.

Step 4 involves the oxidation of α-ketoglutarate and formation of CO2. In this step, α-ketoglutarate is reacted with CoA-SH and NAD+. This is the second oxidation reaction of the citric acid cycle and leads to the formation of succinyl CoA. The enzyme employed for oxidation is α-ketoglutarate dehydrogenase. The reaction of step 4 is:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  9

The final product is succinyl CoA and one molecule of CO2 is released.

(d)

Interpretation Introduction

Interpretation: To determine the number of time oxidation-reduction reaction occur during one turn of the citric acid cycle.

Concept introduction: Citric acid cycle is the third stage of the biochemical energy production process. The cycle includes the reactions in which the acetyl part of acetyl CoA is oxidized and leads to the formation of carbon dioxide and CoA-SH.

An overview of the citric acid cycle is as follows:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  10

Oxidation-reduction reactions are those in which both oxidation and reduction occur simultaneously in the reaction. One species gets oxidized and other gets reduced.

(d)

Expert Solution
Check Mark

Answer to Problem 23.70EP

The oxidation-reduction reaction occurs four times in the citric acid cycle in step 3, 4, 6 and 8.

Explanation of Solution

Step 3 is the first step where both the oxidation and decarboxylation occurs. Step 3 involves the oxidation of isocitrate and formation of CO2. In this step, firstly isocitrate is oxidized by NAD+ to form oxalosuccinate and then decarboxylation takes place to form α-ketoglutarate. The reaction of this step is:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  11

NAD+ acts as oxidizing agent in this step. Isocitrate is oxidized to oxalosuccinate and NAD+ is reduced to form NADH.

Step 4 involves the oxidation of α-ketoglutarate and formation of CO2. In this step, α-ketoglutarate is reacted with CoA-SH and NAD+. This is the second oxidation reaction of the citric acid cycle and leads to the formation of succinyl CoA. The enzyme employed for oxidation is α-ketoglutarate dehydrogenase. The reaction of step 4 is:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  12

NAD+ acts as an oxidizing agent in this step. α-ketoglutarate is oxidized to succinyl CoA and NAD+ is reduced to form NADH.

In step 6, oxidation of succinate occurs to form fumarate. The enzyme involved in this step of the citric acid cycle is succinate dehydrogenase. FAD is the oxidizing agent in this step. This reaction takes place in the inner mitochondrial membrane. The reaction of step 6 is:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  13

Step 8 is an oxidation reaction and the last step of the citric acid cycle. In step 8, L-malate is oxidized to regenerate oxaloacetate with the help of enzyme malate dehydrogenase. NAD+ acts as an oxidizing agent in the reaction.

The reaction of step 8 is:

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP, Chapter 23, Problem 23.70EP , additional homework tip  14

NAD+ acts as an oxidizing agent in this step. L-malate is oxidized to oxaloacetate and NAD+ is reduced to form NADH.

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Chapter 23 Solutions

GENERAL,ORGANIC,+BIO.CHEM.-MINDTAP

Ch. 23.3 - Which of the following statements concerning...Ch. 23.4 - Prob. 1QQCh. 23.4 - Prob. 2QQCh. 23.5 - Prob. 1QQCh. 23.5 - Prob. 2QQCh. 23.5 - Prob. 3QQCh. 23.6 - Which of the following occurs in the second stage...Ch. 23.6 - Which of the following stages in the biochemical...Ch. 23.6 - Prob. 3QQCh. 23.7 - Prob. 1QQCh. 23.7 - Prob. 2QQCh. 23.7 - Prob. 3QQCh. 23.7 - How many NADH and FADH2 molecules are produced,...Ch. 23.7 - Which of the following citric acid cycle...Ch. 23.7 - In which of the following listings of citric acid...Ch. 23.8 - Which of the following is a fuel for the electron...Ch. 23.8 - Prob. 2QQCh. 23.8 - What is the substrate that initially interacts...Ch. 23.8 - The number of fixed enzyme sites in the electron...Ch. 23.8 - In which of the following listings of electron...Ch. 23.8 - Prob. 6QQCh. 23.9 - How many of the four enzyme complexes in the...Ch. 23.9 - Prob. 2QQCh. 23.9 - Prob. 3QQCh. 23.10 - Prob. 1QQCh. 23.10 - Prob. 2QQCh. 23.11 - Prob. 1QQCh. 23.11 - Prob. 2QQCh. 23.11 - Prob. 3QQCh. 23.12 - Prob. 1QQCh. 23.12 - Prob. 2QQCh. 23 - Classify anabolism and catabolism as synthetic or...Ch. 23 - Classify anabolism and catabolism as...Ch. 23 - What is a metabolic pathway?Ch. 23 - Prob. 23.4EPCh. 23 - Classify each of the following processes as...Ch. 23 - Classify each of the following processes as...Ch. 23 - Prob. 23.7EPCh. 23 - Prob. 23.8EPCh. 23 - Prob. 23.9EPCh. 23 - Indicate whether each of the following statements...Ch. 23 - Prob. 23.11EPCh. 23 - Prob. 23.12EPCh. 23 - Prob. 23.13EPCh. 23 - Prob. 23.14EPCh. 23 - Specify, by name and by number present, the...Ch. 23 - Prob. 23.16EPCh. 23 - Prob. 23.17EPCh. 23 - Prob. 23.18EPCh. 23 - Prob. 23.19EPCh. 23 - Prob. 23.20EPCh. 23 - Prob. 23.21EPCh. 23 - Prob. 23.22EPCh. 23 - Write a generalized chemical equation, containing...Ch. 23 - Prob. 23.24EPCh. 23 - Prob. 23.25EPCh. 23 - Prob. 23.26EPCh. 23 - Draw each of the following types of block diagrams...Ch. 23 - Prob. 23.28EPCh. 23 - What is the name of the B vitamin present in each...Ch. 23 - Prob. 23.30EPCh. 23 - Prob. 23.31EPCh. 23 - Prob. 23.32EPCh. 23 - Prob. 23.33EPCh. 23 - Prob. 23.34EPCh. 23 - Prob. 23.35EPCh. 23 - Prob. 23.36EPCh. 23 - Prob. 23.37EPCh. 23 - Prob. 23.38EPCh. 23 - Prob. 23.39EPCh. 23 - Prob. 23.40EPCh. 23 - Prob. 23.41EPCh. 23 - Prob. 23.42EPCh. 23 - Prob. 23.43EPCh. 23 - Prob. 23.44EPCh. 23 - Prob. 23.45EPCh. 23 - Prob. 23.46EPCh. 23 - Prob. 23.47EPCh. 23 - Prob. 23.48EPCh. 23 - Prob. 23.49EPCh. 23 - Prob. 23.50EPCh. 23 - Prob. 23.51EPCh. 23 - Prob. 23.52EPCh. 23 - Prob. 23.53EPCh. 23 - Prob. 23.54EPCh. 23 - Prob. 23.55EPCh. 23 - Prob. 23.56EPCh. 23 - Prob. 23.57EPCh. 23 - Prob. 23.58EPCh. 23 - List, by name, the four general stages of the...Ch. 23 - Prob. 23.60EPCh. 23 - Prob. 23.61EPCh. 23 - Prob. 23.62EPCh. 23 - Prob. 23.63EPCh. 23 - Prob. 23.64EPCh. 23 - Prob. 23.65EPCh. 23 - Prob. 23.66EPCh. 23 - Prob. 23.67EPCh. 23 - Prob. 23.68EPCh. 23 - Prob. 23.69EPCh. 23 - Prob. 23.70EPCh. 23 - Prob. 23.71EPCh. 23 - Prob. 23.72EPCh. 23 - Prob. 23.73EPCh. 23 - Prob. 23.74EPCh. 23 - Prob. 23.75EPCh. 23 - Prob. 23.76EPCh. 23 - Prob. 23.77EPCh. 23 - Prob. 23.78EPCh. 23 - Prob. 23.79EPCh. 23 - Prob. 23.80EPCh. 23 - Prob. 23.81EPCh. 23 - Prob. 23.82EPCh. 23 - Prob. 23.83EPCh. 23 - Prob. 23.84EPCh. 23 - Prob. 23.85EPCh. 23 - Prob. 23.86EPCh. 23 - Prob. 23.87EPCh. 23 - Prob. 23.88EPCh. 23 - Indicate whether each of the following changes...Ch. 23 - Prob. 23.90EPCh. 23 - Prob. 23.91EPCh. 23 - Prob. 23.92EPCh. 23 - Which electron carrier shuttles electrons between...Ch. 23 - Prob. 23.94EPCh. 23 - Prob. 23.95EPCh. 23 - Prob. 23.96EPCh. 23 - Prob. 23.97EPCh. 23 - Prob. 23.98EPCh. 23 - Prob. 23.99EPCh. 23 - Prob. 23.100EPCh. 23 - Put the following substances in the correct order...Ch. 23 - Prob. 23.102EPCh. 23 - Prob. 23.103EPCh. 23 - Prob. 23.104EPCh. 23 - Prob. 23.105EPCh. 23 - Prob. 23.106EPCh. 23 - Prob. 23.107EPCh. 23 - Prob. 23.108EPCh. 23 - Prob. 23.109EPCh. 23 - Prob. 23.110EPCh. 23 - How many protons cross the inner mitochondrial...Ch. 23 - How many protons cross the inner mitochondrial...Ch. 23 - Prob. 23.113EPCh. 23 - Prob. 23.114EPCh. 23 - Prob. 23.115EPCh. 23 - Prob. 23.116EPCh. 23 - Prob. 23.117EPCh. 23 - Prob. 23.118EPCh. 23 - Prob. 23.119EPCh. 23 - Prob. 23.120EPCh. 23 - Prob. 23.121EPCh. 23 - Prob. 23.122EPCh. 23 - Prob. 23.123EPCh. 23 - Prob. 23.124EPCh. 23 - Prob. 23.125EPCh. 23 - Prob. 23.126EPCh. 23 - Prob. 23.127EPCh. 23 - Prob. 23.128EPCh. 23 - Indicate whether or not each of the following B...Ch. 23 - Prob. 23.130EPCh. 23 - Prob. 23.131EPCh. 23 - Prob. 23.132EP
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