In DNA the oxygen atom is lost from the pentose sugar molecule at this carbon

Options

A. 5
B. 4
C. 2
D. 1

Answer

To solve the question regarding the loss of an oxygen atom in the pentose sugar of DNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Structure of DNA**:
- DNA, or deoxyribonucleic acid, consists of a sugar, phosphate group, and nitrogenous bases. The sugar in DNA is a pentose sugar.

2. **Identifying the Pentose Sugar**:
- The pentose sugar in DNA is called deoxyribose. It is a five-carbon sugar.

3. **Analyzing the Carbon Atoms**:
- The carbon atoms in deoxyribose are numbered from 1' to 5'. The structure of deoxyribose includes:
- 1' carbon: Attached to the nitrogenous base.
- 2' carbon: Where the oxygen atom is lost in DNA.
- 3' carbon: Contains a hydroxyl group (-OH).
- 4' carbon: Part of the ring structure.
- 5' carbon: Attached to the phosphate group.

4. **Identifying the Loss of Oxygen**:
- In ribose (the sugar found in RNA), the 2' carbon has a hydroxyl group (-OH). However, in deoxyribose, this hydroxyl group is replaced by a hydrogen atom (H), meaning that the oxygen atom is lost from the 2' carbon.

5. **Conclusion**:
- Therefore, the oxygen atom is lost from the pentose sugar molecule at the **2' carbon**.

### Final Answer:
The oxygen atom is lost from the pentose sugar molecule at the **2' carbon**.

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