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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3:16 minutes

Problem 80c

Textbook Question

Refer to the diagram of the citric acid cycle in Figure 12.11 to answer each of the following:
c. Name the reaction that is coupled to GTP formation.

Verified step by step guidance

Identify the step in the citric acid cycle where GTP (or ATP, depending on the organism) is formed. This occurs during the conversion of succinyl-CoA to succinate.

Understand that this reaction is catalyzed by the enzyme succinyl-CoA synthetase (also known as succinate thiokinase).

Recognize that the reaction involves substrate-level phosphorylation, where a high-energy thioester bond in succinyl-CoA is used to drive the formation of GTP (or ATP).

Note that the reaction can be summarized as:

{succinyl}_{- CoA} + GDP + P i \to succinate + GTP + CoA - SH

Conclude that the reaction coupled to GTP formation is the conversion of succinyl-CoA to succinate, which is an example of substrate-level phosphorylation.

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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 series of chemical reactions used by all aerobic organisms to generate energy. It takes place in the mitochondria and involves the oxidation of acetyl-CoA to produce ATP, NADH, and FADH2, which are crucial for cellular respiration.

GTP Formation

GTP (guanosine triphosphate) formation occurs during the citric acid cycle, specifically in the conversion of succinyl-CoA to succinate. This reaction is catalyzed by the enzyme succinyl-CoA synthetase and is an example of substrate-level phosphorylation, where a phosphate group is directly transferred to GDP to form GTP.

Coupled Reactions

Coupled reactions involve linking an energetically unfavorable reaction with a favorable one to drive the overall process. In the context of the citric acid cycle, the reaction that produces GTP is coupled with the hydrolysis of the thioester bond in succinyl-CoA, which releases energy and makes the formation of GTP thermodynamically favorable.