The number of oxidations, substrate level phosphorylations respectively in HDP pathway are

Options

A. 1, 1
B. 2, 1
C. 1, 2
D. 2, 2

Answer

To solve the question regarding the number of oxidations and substrate level phosphorylations in the HDP pathway, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the HDP Pathway**: The HDP (Hexose Diphosphate) pathway is a metabolic pathway that involves the conversion of glucose into pyruvate. It is important to identify the key reactions that occur in this pathway.

2. **Identify Oxidation Reactions**:
- The first oxidation occurs when NADH + H⁺ is converted into NAD⁺. This is a key step in the pathway where electrons are transferred, resulting in the oxidation of NADH.
- The second oxidation occurs during the conversion of 1,3-bisphosphoglycerate to glyceraldehyde 3-phosphate. This reaction also involves the loss of electrons, indicating another oxidation step.

3. **Count the Number of Oxidations**: From the above analysis, we can conclude that there are **2 oxidation reactions** in the HDP pathway.

4. **Identify Substrate Level Phosphorylation**:
- Substrate level phosphorylation occurs when 3-phosphoglycerate is converted into 1,3-bisphosphoglycerate. This reaction involves the direct transfer of a phosphate group to ADP, forming ATP.

5. **Count the Number of Substrate Level Phosphorylations**: Based on the identified reaction, we find that there is **1 substrate level phosphorylation** in the HDP pathway.

6. **Summarize the Results**: Therefore, the total number of oxidations is **2**, and the total number of substrate level phosphorylations is **1**.

7. **Final Answer**: The answer to the question is: **2 oxidations and 1 substrate level phosphorylation**.