Which of the following phosphorylation occurs in power house of eukaryotic cell?

Options

A. Oxidative phosphorylation
B. Substrate level phosphorylation
C. Photophosphorylation
D. Both (a) and (b)

Answer

To solve the question "Which of the following phosphorylation occurs in the powerhouse of eukaryotic cell?", we need to analyze the types of phosphorylation mentioned and their locations within the cell.

### Step-by-Step Solution:

1. **Identify the Powerhouse of the Cell**:
- The powerhouse of the eukaryotic cell is the mitochondria. This is where ATP (adenosine triphosphate) is produced through various biochemical processes.

2. **Understand the Types of Phosphorylation**:
- **Oxidative Phosphorylation**: This process occurs in the inner mitochondrial membrane. It involves the electron transport chain and chemiosmosis, leading to the production of ATP from ADP and inorganic phosphate (Pi) using energy derived from electrons.
- **Substrate-Level Phosphorylation**: This occurs during the Krebs cycle (also known as the citric acid cycle), which takes place in the mitochondrial matrix. In this process, a phosphate group is directly transferred to ADP to form ATP from a substrate molecule.
- **Photophosphorylation**: This process occurs in chloroplasts, specifically in the thylakoid membranes during photosynthesis. It is not related to the mitochondria.

3. **Determine Which Phosphorylation Types Occur in Mitochondria**:
- From the definitions, we can conclude that both oxidative phosphorylation and substrate-level phosphorylation occur in the mitochondria.

4. **Select the Correct Answer**:
- Since both oxidative phosphorylation and substrate-level phosphorylation occur in the mitochondria, the correct answer to the question is option D, which states that both A (oxidative phosphorylation) and B (substrate-level phosphorylation) are correct.

### Final Answer:
The correct option is D: Both A and B (oxidative phosphorylation and substrate-level phosphorylation) occur in the powerhouse of eukaryotic cells.