Textbook Question
If there are no reactions in the citric acid cycle that use oxygen, O2, why does the cycle operate only in aerobic conditions?
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Ch.18 Metabolic Pathways and ATP Production
Timberlake14thChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9781292472249
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Table of contents
- Ch.1 Chemistry in Our Lives19
- Ch.2 Chemistry and Measurements80
- Ch.3 Matter and Energy53
- Ch.4 Atoms and Elements58
- Ch.5 Nuclear Chemistry42
- Ch.6 Ionic and Molecular Compounds57
- Ch.7 Chemical Quantities and Reactions38
- Ch.8 Gases30
- Ch.9 Solutions50
- Ch.10 Acids and Bases and Equilibrium64
- Ch.11 Introduction to Organic Chemistry: Hydrocarbons77
- Ch.12 Alcohols, Thiols, Ethers, Aldehydes, and Ketones82
- Ch.13 Carbohydrates54
- Ch.14 Carboxylic Acids, Esters, Amines, and Amides91
- Ch.15 Lipids61
- Ch.16 Amino Acids, Proteins, and Enzymes84
- Ch.17 Nucleic Acids and Protein Synthesis86
- Ch.18 Metabolic Pathways and ATP Production73
Timberlake14thChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9781292472249Not the one you use?Change textbook
Chapter 18, Problem 92
What citric acid cycle intermediate(s) can be produced from the carbon atoms of each of the following amino acids?
a. tryptophan
b. histidine
c. threonine
d. phenylalanine
Verified step by step guidance1
Step 1: Understand the citric acid cycle (also known as the Krebs cycle or TCA cycle). It is a series of chemical reactions used by all aerobic organisms to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins. Amino acids can be converted into intermediates of the cycle through various metabolic pathways.
Step 2: Analyze the amino acid tryptophan. Tryptophan can be metabolized into intermediates such as pyruvate or acetyl-CoA, which can then enter the citric acid cycle. Additionally, it can contribute to the production of intermediates like α-ketoglutarate.
Step 3: Examine histidine. Histidine is converted into glutamate through a series of reactions. Glutamate can then be deaminated to form α-ketoglutarate, which is an intermediate in the citric acid cycle.
Step 4: Investigate threonine. Threonine can be metabolized into acetyl-CoA or glycine. Acetyl-CoA directly enters the citric acid cycle, while glycine can contribute to the formation of intermediates like pyruvate.
Step 5: Consider phenylalanine. Phenylalanine is converted into tyrosine, which can then be further metabolized into fumarate and acetoacetate. Fumarate is a direct intermediate of the citric acid cycle.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Citric Acid Cycle (Krebs Cycle)
The citric acid cycle, also known as the Krebs cycle, is a key metabolic pathway that takes place in the mitochondria. It involves a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins. Understanding this cycle is essential for determining how amino acids can be converted into intermediates that enter the cycle.
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Citric Acid Cycle Summary Concept 12
Amino Acid Catabolism
Amino acid catabolism refers to the process by which amino acids are broken down to produce energy or to create metabolic intermediates. This process can lead to the production of various citric acid cycle intermediates, depending on the specific amino acid. Recognizing the pathways of catabolism for each amino acid is crucial for answering the question regarding their conversion into citric acid cycle intermediates.
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2:21Amino Acid Catabolism: Amino Group Concept 1
Metabolic Intermediates
Metabolic intermediates are compounds that form in the middle of metabolic pathways and can be used in various biochemical reactions. In the context of the citric acid cycle, intermediates such as citrate, alpha-ketoglutarate, and succinyl-CoA can be derived from the breakdown of certain amino acids. Identifying which intermediates can be produced from specific amino acids is key to understanding their role in energy metabolism.
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Related Practice
Textbook Question
In the chemiosmotic model, how is energy provided to synthesize ATP?
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Textbook Question
One cell at work may break down 2 million (2 000 000) ATP molecules in one second. Some researchers estimate that the human body has about 1013 cells.
b. If ATP has a molar mass of 507 g/mole, how many grams of ATP are hydrolyzed in one day?
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Textbook Question
State if each of the following processes release or require ATP:
f. first six reactions of glycolysis
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Textbook Question
State if each of the following processes release or require ATP:
g. activation of a fatty acid
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