Which of the following bases contains two keto groups ?

Options

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

Answer

To determine which of the following bases contains two keto groups, we need to analyze the structures of the bases mentioned. The bases we will consider are adenine, guanine, thymine, and cytosine.

**Step 1: Understand what a keto group is.**
A keto group is a functional group characterized by a carbon atom double-bonded to an oxygen atom (C=O). In organic chemistry, it is typically found in ketones and can also appear in other compounds.

**Step 2: Analyze the structure of each base.**
1. **Adenine**: Adenine has an amine group and does not contain any keto groups.
2. **Guanine**: Guanine has one keto group in its structure.
3. **Thymine**: Thymine has two keto groups in its structure. The structure of thymine includes two carbonyl (C=O) groups.
4. **Cytosine**: Cytosine contains one keto group and an amine group.

**Step 3: Identify the base with two keto groups.**
From the analysis, we find that thymine is the only base that contains two keto groups.

**Final Answer: Thymine contains two keto groups.**

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