The reactions of Krebs/citric acid cycle take place

Options

A. In the cytoplasm
B. In ER
C. In matrix of mitochondira
D. On the surface of mitochondria

Answer

To answer the question about where the reactions of the Krebs or citric acid cycle take place, we can follow these steps:

**Step 1: Understand the Krebs Cycle**
The Krebs cycle, also known as the citric acid cycle, is a key metabolic pathway that is part of cellular respiration. It plays a crucial role in energy production within cells.

**Step 2: Identify the Location of the Krebs Cycle**
The Krebs cycle occurs after the link reaction (also known as the pyruvate oxidation), which converts pyruvate into acetyl-CoA. The Krebs cycle itself takes place in a specific part of the cell.

**Step 3: Determine the Correct Location**
The Krebs cycle takes place in the matrix of the mitochondria. This is the innermost compartment of the mitochondria, where various enzymes involved in the Krebs cycle are located.

**Step 4: Eliminate Incorrect Options**
- The cytoplasm is where glycolysis occurs, not the Krebs cycle.
- The endoplasmic reticulum (ER) is involved in protein and lipid synthesis, not in the Krebs cycle.
- The surface of the mitochondria is not where the Krebs cycle occurs; it is specifically in the matrix.

**Step 5: Conclude the Answer**
Based on the above analysis, the correct answer is that the reactions of the Krebs or citric acid cycle take place in the matrix of mitochondria.

**Final Answer:**
The reactions of the Krebs/citric acid cycle take place in the matrix of mitochondria.

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