Table of contents

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

21. The Generation of Biochemical Energy

The Citric Acid Cycle

GOB Chemistry

21. The Generation of Biochemical Energy

The Citric Acid Cycle

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4:57 minutes

Problem 98e

Textbook Question

Which of the following molecules will produce the most ATP per mole?
e. α-ketoglutarate or fumarate in one turn of the citric acid cycle

Verified step by step guidance

Understand the context: The citric acid cycle (also known as the Krebs cycle) is a central metabolic pathway that generates energy in the form of ATP, NADH, and FADH₂. Each intermediate in the cycle contributes differently to the production of ATP.

Identify the molecules in question: α-ketoglutarate and fumarate are intermediates in the citric acid cycle. α-ketoglutarate is converted to succinyl-CoA, while fumarate is converted to malate in subsequent steps of the cycle.

Analyze the energy yield of each molecule: The conversion of α-ketoglutarate to succinyl-CoA produces one molecule of NADH. NADH is later used in the electron transport chain to generate approximately 2.5 ATP. Additionally, the conversion of succinyl-CoA to succinate generates one molecule of GTP (equivalent to 1 ATP).

Compare this to fumarate: The conversion of fumarate to malate does not directly produce NADH, FADH₂, or ATP. However, the subsequent conversion of malate to oxaloacetate produces one molecule of NADH, which generates approximately 2.5 ATP in the electron transport chain.

Conclude: Since α-ketoglutarate produces both NADH and GTP (equivalent to ATP) in its conversion to succinyl-CoA and succinate, it yields more ATP per mole compared to fumarate, which only indirectly contributes to ATP production through NADH formation in a later step.

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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 key metabolic pathway that occurs in the mitochondria. It involves a series of enzymatic reactions that convert acetyl-CoA into carbon dioxide and high-energy electron carriers, such as NADH and FADH2. These carriers are crucial for ATP production in the electron transport chain, making the cycle essential for cellular respiration.

ATP Yield from Metabolites

Different metabolites yield varying amounts of ATP when oxidized. For instance, α-ketoglutarate and fumarate are intermediates in the citric acid cycle, but their ATP yield differs based on the number of high-energy electron carriers produced during their conversion. Understanding the specific ATP yield from each metabolite helps in determining which one is more efficient in energy production.

Oxidative Phosphorylation

Oxidative phosphorylation is the final stage of cellular respiration, where the energy from electron carriers (NADH and FADH2) is used to generate ATP. This process occurs in the inner mitochondrial membrane and involves the electron transport chain and ATP synthase. The efficiency of ATP production from different substrates in the citric acid cycle is ultimately linked to how effectively their electrons are transferred through this pathway.