Which of the following molecules are involved in the formation of ATP by substrate level
phosphorylation during glycolysis?
A. 1, 3-bisphosphoglycerate
B. Glucose 6-phosphate
C. Phosphoenolpyruvate
D. Fructose 1, 6-bisphosphate
1. A, C
2. C, D
3. A, D
4. B, C

 

Introduction to ATP Formation in Glycolysis

Glycolysis is a fundamental metabolic pathway in which glucose is converted into pyruvate, producing energy in the form of ATP and NADH. One of the key mechanisms for ATP generation during glycolysis is substrate-level phosphorylation. In this process, a phosphate group is directly transferred from a high-energy substrate to ADP, forming ATP. This article explains which molecules are involved in ATP formation by substrate-level phosphorylation and why they are important for cellular metabolism.

Key Phrase: ATP Formation by Substrate-Level Phosphorylation

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Question and Answer

Question:
Which of the following molecules are involved in the formation of ATP by substrate-level phosphorylation during glycolysis?

Options:

• A. 1,3-bisphosphoglycerate
• B. Glucose 6-phosphate
• C. Phosphoenolpyruvate
• D. Fructose 1,6-bisphosphate

Correct Answer:
✔️ Option 1: A, C

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ATP Formation by Substrate-Level Phosphorylation

Substrate-level phosphorylation is a direct method of generating ATP in cells. This process occurs when a high-energy phosphate group is transferred from an intermediate molecule to ADP, producing ATP.

1. First ATP Formation Step

• Substrate: 1,3-bisphosphoglycerate
• Enzyme: Phosphoglycerate kinase
• Reaction:

1,3−bisphosphoglycerate+ADP→3−phosphoglycerate+ATP   

2. Second ATP Formation Step

• Substrate: Phosphoenolpyruvate (PEP)
• Enzyme: Pyruvate kinase
• Reaction:

Phosphoenolpyruvate+ADP→Pyruvate+ATP  

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Why Other Options Are Incorrect

Glucose 6-phosphate – It is involved in the early stages of glycolysis but does not participate in ATP formation through substrate-level phosphorylation.
Fructose 1,6-bisphosphate – It is a key intermediate in glycolysis but does not contribute to ATP production through direct phosphate transfer.

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Importance of ATP Formation by Substrate-Level Phosphorylation

• Glycolysis occurs in the cytoplasm and does not require oxygen.
• Substrate-level phosphorylation provides ATP even under anaerobic conditions.
• It generates a total of 4 ATP molecules per glucose molecule (net gain = 2 ATP).

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How ATP Formation is Linked to Metabolism

• ATP produced by substrate-level phosphorylation is used in various cellular processes, including:
  • Protein synthesis
  • Active transport of molecules
  • Muscle contraction

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Relevance for Competitive Exams

Understanding glycolysis and ATP formation is essential for exams like:
DBT BET JRF
CSIR NET Life Science
IIT JAM
GATE Biotechnology

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Why 1,3-bisphosphoglycerate and PEP Are Correct Answers

• Both molecules have high phosphoryl transfer potential.
• They directly transfer a phosphate group to ADP, forming ATP.
• This reaction is catalyzed by specific kinases:
  • Phosphoglycerate kinase (for 1,3-bisphosphoglycerate)
  • Pyruvate kinase (for phosphoenolpyruvate)

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Conclusion

The correct molecules involved in ATP formation by substrate-level phosphorylation during glycolysis are 1,3-bisphosphoglycerate and phosphoenolpyruvate. These high-energy intermediates play a vital role in ATP generation, ensuring that cells have sufficient energy for metabolic processes. Understanding substrate-level phosphorylation is crucial for acing exams like DBT BET JRF, CSIR NET Life Science, IIT JAM, and GATE Biotechnology.