Which one is inhibited if the cells contain excess of ATP

Options

A. Krebs cycle
B. Glycolysis
C. Oxidative phosphorylation
D. Electron transport

Explanation

**Step-by-Step Solution:**

1. **Understanding ATP and Its Role**: ATP (adenosine triphosphate) is the primary energy carrier in cells. When cells have sufficient energy, they regulate metabolic pathways to prevent overproduction of ATP.

2. **Excess ATP and Feedback Mechanism**: When there is an excess of ATP in the cell, it triggers a negative feedback mechanism. This means that the presence of high levels of ATP signals the cell to slow down or inhibit certain metabolic processes.

3. **Identifying the Key Enzyme**: The enzyme involved in this feedback mechanism is phosphofructokinase (PFK). PFK plays a crucial role in glycolysis, which is the pathway that breaks down glucose to produce ATP.

4. **Glycolysis Process**: During glycolysis, glucose is converted into fructose-1,6-bisphosphate, and phosphofructokinase is responsible for catalyzing one of the key steps in this process.

5. **Inhibition of Glycolysis**: When ATP levels are high, phosphofructokinase is inhibited. This inhibition prevents glycolysis from proceeding, thus reducing the production of more ATP.

6. **Conclusion**: Therefore, if the cells contain an excess of ATP, the process that is inhibited is glycolysis, due to the action of the enzyme phosphofructokinase.

**Final Answer**: Glycolysis is inhibited when there is an excess of ATP in the cells.

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