Amino acid having sulphur is

Options

A. Cysteine
B. Lysine
C. Leucine
D. Isoleucine.

Answer

To determine which amino acid contains sulfur, we can analyze the provided options: cysteine, lysine, leucine, and isoleucine.

### Step-by-Step Solution:

1. **Understand the Structure of Amino Acids**:
- All amino acids have a general structure that includes an amino group (NH2), a carboxyl group (COOH), a hydrogen atom, and a variable R group (side chain) that distinguishes one amino acid from another.

2. **Examine Each Option**:
- **Cysteine**: The R group of cysteine is CH2SH. This indicates the presence of a sulfur atom (S) in its structure.
- **Lysine**: The R group of lysine is (CH2)4NH2. There is no sulfur present in this structure.
- **Leucine**: The R group of leucine is CH2CH(CH3)2. This structure also does not contain sulfur.
- **Isoleucine**: The R group of isoleucine is CH(CH3)CH2CH3. Similar to leucine, this structure lacks sulfur.

3. **Identify the Amino Acid with Sulfur**:
- From the analysis, cysteine is the only amino acid among the options that contains sulfur in its structure.

4. **Conclusion**:
- Therefore, the amino acid that has sulfur is **cysteine**.

### Final Answer:
Cysteine is the amino acid having sulfur.