Which one is made of a single ring of atoms ?

Options

A. Guanine
B. Adenine
C. Thymine
D. Glycine.

Answer

To determine which molecule is made of a single ring of atoms, we need to analyze the types of nitrogenous bases found in nucleic acids (DNA and RNA). These bases can be categorized into two groups: pyrimidines and purines.

### Step-by-Step Solution:

1. **Identify the Types of Nitrogenous Bases**:
- Nitrogenous bases are classified into two categories:
- **Pyrimidines**: These have a single ring structure.
- **Purines**: These have a double ring structure.

2. **List the Examples of Each Type**:
- **Pyrimidines**: Examples include cytosine, thymine, and uracil.
- **Purines**: Examples include adenine and guanine.

3. **Focus on the Question**:
- The question specifically asks for a nitrogenous base that is made up of a single ring of atoms.

4. **Analyze the Options**:
- If the options include guanine, adenine, thymine, and glycine:
- **Guanine**: This is a purine (double ring).
- **Adenine**: This is also a purine (double ring).
- **Thymine**: This is a pyrimidine (single ring).
- **Glycine**: This is an amino acid and does not have a ring structure.

5. **Select the Correct Answer**:
- Among the options, **thymine** is the only nitrogenous base that is made up of a single ring of atoms. Therefore, the correct answer is **thymine**.

### Final Answer:
**Thymine** is made of a single ring of atoms.

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