6 - amino purine is

Options

A. Adenosine
B. Adenine
C. Cytosine
D. Thymine

Answer

To solve the question "6-amino purine is:", we need to identify which of the given options corresponds to the compound known as 6-amino purine. The options provided are adenosine, adenine, cytosine, and thymine.

### Step-by-Step Solution:

1. **Understanding the Term "6-Amino Purine":**
- The term "6-amino purine" refers to a purine base that has an amino group (-NH2) attached to the sixth carbon of the purine ring structure.

2. **Identifying Purines:**
- Purines are a class of nitrogenous bases that include adenine and guanine. The structure of purines consists of a fused double-ring system.

3. **Analyzing the Options:**
- **Adenosine:** This is a nucleoside composed of adenine and ribose. It is not simply a purine base.
- **Adenine:** This is a purine base that has an amino group at the 6th position, making it a candidate for 6-amino purine.
- **Cytosine:** This is a pyrimidine base, not a purine.
- **Thymine:** This is also a pyrimidine base.

4. **Confirming the Structure of Adenine:**
- The structure of adenine can be drawn and analyzed. The amino group is indeed located at the 6th position of the purine structure.
- Drawing the structure:
- The numbering of the carbons in the purine ring shows that the amino group is attached to carbon 6.

5. **Conclusion:**
- Based on the analysis and the structure of adenine, we conclude that 6-amino purine is adenine.

### Final Answer:
- The correct answer is **adenine**.