Textbook Question
Where in the cell does the citric acid cycle take place?
Ch.21 The Generation of Biochemical Energy
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch.1 Matter and Measurements27
- Ch.2 Atoms and the Periodic Table20
- Ch.3 Ionic Compounds8
- Ch.4 Molecular Compounds23
- Ch.5 Classification & Balancing of Chemical Reactions12
- Ch.6 Chemical Reactions: Mole and Mass Relationships28
- Ch.7 Chemical Reactions: Energy, Rate and Equilibrium64
- Ch.8 Gases, Liquids and Solids24
- Ch.9 Solutions52
- Ch.10 Acids and Bases25
- Ch.11 Nuclear Chemistry22
- Ch.12 Introduction to Organic Chemistry: Alkanes57
- Ch.13 Alkenes, Alkynes, and Aromatic Compounds47
- Ch.14 Some Compounds with Oxygen, Sulfur, or a Halogen50
- Ch.15 Aldehydes and Ketones45
- Ch.16 Amines42
- Ch.17 Carboxylic Acids and Their Derivatives57
- Ch.18 Amino Acids and Proteins82
- Ch.19 Enzymes and Vitamins63
- Ch.20 Carbohydrates44
- Ch.21 The Generation of Biochemical Energy65
- Ch.22 Carbohydrate Metabolism45
- Ch.23 Lipids42
- Ch.24 Lipid Metabolism33
- Ch.25 Protein and Amino Acid Metabolism24
- Ch.26 Nucleic Acids and Protein Synthesis45
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187Not the one you use?Change textbook
Chapter 21, Problem 55a
Look at the eight steps of the citric acid cycle (Figure 21.8) and answer the following questions:
a. Which steps involve oxidation reactions?
Verified step by step guidance1
Step 1: Understand the context of the citric acid cycle. The citric acid cycle, also known as the Krebs cycle or TCA cycle, is a series of chemical reactions used by aerobic organisms to generate energy through the oxidation of acetyl-CoA. Oxidation reactions involve the loss of electrons, often accompanied by the reduction of an electron carrier such as NAD⁺ or FAD.
Step 2: Review the eight steps of the citric acid cycle. Refer to Figure 21.8 or a similar diagram of the cycle. Identify the specific steps where NAD⁺ or FAD is reduced to NADH or FADH₂, as these indicate oxidation reactions of the substrate.
Step 3: Identify the steps where NAD⁺ is reduced to NADH. These occur during the oxidation of isocitrate to α-ketoglutarate, α-ketoglutarate to succinyl-CoA, and malate to oxaloacetate. These are oxidation reactions because the substrate loses electrons.
Step 4: Identify the step where FAD is reduced to FADH₂. This occurs during the oxidation of succinate to fumarate. Again, this is an oxidation reaction because the substrate loses electrons while FAD gains them.
Step 5: Summarize the oxidation steps. The oxidation reactions in the citric acid cycle occur in the following steps: (1) isocitrate to α-ketoglutarate, (2) α-ketoglutarate to succinyl-CoA, (3) succinate to fumarate, and (4) malate to oxaloacetate. These steps involve the transfer of electrons to NAD⁺ or FAD, forming NADH or FADH₂.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Citric Acid Cycle
The citric acid cycle, also known as the Krebs cycle, is a series of enzymatic reactions that occur in the mitochondria, playing a crucial role in cellular respiration. It processes acetyl-CoA derived from carbohydrates, fats, and proteins into carbon dioxide and high-energy electron carriers, such as NADH and FADH2, which are essential for ATP production.
Recommended video:
Guided course
2:31
Citric Acid Cycle Summary Concept 12
Oxidation Reactions
Oxidation reactions involve the loss of electrons from a molecule, often accompanied by the addition of oxygen or the removal of hydrogen. In the context of the citric acid cycle, these reactions are vital for energy production, as they convert substrates into more oxidized forms, facilitating the transfer of electrons to electron carriers.
Recommended video:
Guided course
1:32Alcohol Reactions Oxidation Reactions Example 1
Enzymatic Steps in the Cycle
The citric acid cycle consists of eight distinct enzymatic steps, each catalyzed by specific enzymes. Understanding which steps involve oxidation is crucial for grasping how energy is extracted from substrates, as these steps are where electron carriers are generated, ultimately contributing to the cell's energy economy.
Recommended video:
Guided course
5:08Steps of DNA Replication Concept 1
Related Practice
Textbook Question
Look at the eight steps of the citric acid cycle (Figure 21.8) and answer the following questions:
c. Which step or steps involve a hydration reaction?
Textbook Question
What is the purpose of the citric acid cycle?
Textbook Question
Look at the eight steps of the citric acid cycle (Figure 21.8) and answer the following questions:
b. Which steps involve decarboxylation (loss of CO2)?
Textbook Question
What is the final fate of the carbons in acetyl-CoA after several turns of the citric acid cycle?
Textbook Question
How many NADH and how many FADH2 molecules are formed in the citric acid cycle?