Which of the following aminoacid does not contain S - atom

Options

A. Serine
B. Lysine
C. Tyrosine
D. Cysteine

Explanation

To determine which of the following amino acids does not contain a sulfur (S) atom, we will analyze the structures of the given amino acids: serine, lysine, tyrosine, and cysteine.

### Step-by-Step Solution:

1. **Identify the Amino Acids**: The amino acids given are:
- Serine
- Lysine
- Tyrosine
- Cysteine

2. **Draw the Structures**:
- **Serine**: The structure of serine includes an amino group (NH2), a carboxyl group (COOH), and a hydroxyl group (OH). It does not contain sulfur.
- **Lysine**: The structure of lysine includes an amino group (NH2), a carboxyl group (COOH), and a long aliphatic chain with an amino group at the end. It does not contain sulfur.
- **Tyrosine**: The structure of tyrosine includes an amino group (NH2), a carboxyl group (COOH), and a phenolic hydroxyl group (OH). It does not contain sulfur.
- **Cysteine**: The structure of cysteine includes an amino group (NH2), a carboxyl group (COOH), and a thiol group (SH). This is the only amino acid among the four that contains sulfur.

3. **Conclusion**: After analyzing the structures, we find that:
- **Cysteine** contains sulfur.
- **Serine**, **Lysine**, and **Tyrosine** do not contain sulfur.

Thus, the amino acids that do not contain a sulfur atom are **Serine**, **Lysine**, and **Tyrosine**. However, the question asks for a single amino acid that does not contain sulfur, and since cysteine is the only one that does, the answer is:

**Answer**: The amino acid that does not contain a sulfur atom is **Serine** (or Lysine or Tyrosine, depending on the context of the question).