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 given options one by one. The options provided are:

1. Cysteine
2. Lysine
3. Leucine
4. Isoleucine

### Step-by-Step Solution:

**Step 1: Identify the amino acids.**
- The four options are Cysteine, Lysine, Leucine, and Isoleucine.

**Step 2: Analyze the structure of each amino acid.**
- **Cysteine**: The structure includes a thiol group (-SH), which contains sulfur.
- **Lysine**: The structure does not contain sulfur; it has an amino group and a long carbon chain.
- **Leucine**: The structure also does not contain sulfur; it has branched carbon chains.
- **Isoleucine**: Similar to Leucine, it has a branched structure without sulfur.

**Step 3: Compare the structures.**
- Upon comparing the structures, only Cysteine contains a sulfur atom in the form of the thiol group (-SH).

**Step 4: Conclude the answer.**
- Therefore, the amino acid that contains sulfur is **Cysteine**.

### Final Answer:
Cysteine is the amino acid that contains sulfur.

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