Sulphur is a constituents of which of the following amino acids?

Options

A. Threonine
B. Cysteine
C. Methionine
D. both b and c

Explanation

To answer the question "Sulphur is a constituent of which of the following amino acids?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Role of Amino Acids**:
- Amino acids are the building blocks of proteins. There are 20 standard amino acids that link together to form proteins through peptide bonds.

2. **Identify the Amino Acids**:
- We need to identify which of the amino acids contain sulfur in their structure.

3. **List Common Amino Acids**:
- The common amino acids include alanine, glycine, serine, cysteine, methionine, and others.

4. **Focus on Sulfur-Containing Amino Acids**:
- Among the amino acids, cysteine and methionine are known to contain sulfur.

5. **Analyze the Structures**:
- Cysteine has a thiol (-SH) group in its side chain (R group), which is where the sulfur is located.
- Methionine contains a thioether (-S-) in its side chain, which also includes sulfur.

6. **Conclude the Answer**:
- Therefore, the amino acids that contain sulfur are cysteine and methionine.

### Final Answer:
Sulphur is a constituent of cysteine and methionine.

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