From the following, how many amino acids contain sulphur in their chemical structure?
Methionine, histidine, threonine, cysteine, alanine, tryptophan, valine

Options

A. Three
B. Five
C. Two
D. Four

Answer

To determine how many amino acids from the given list contain sulfur in their chemical structure, we will analyze each amino acid one by one.

### Step 1: List the amino acids
The amino acids provided in the question are:
1. Methionine
2. Histidine
3. Threonine
4. Cysteine
5. Alanine
6. Tryptophan
7. Valine

### Step 2: Identify sulfur-containing amino acids
Now, we will check each amino acid to see if it contains sulfur:

1. **Methionine**:
- Chemical structure: C5H11NO2S
- Contains sulfur. (Yes)

2. **Histidine**:
- Chemical structure: C6H9N3O2
- Does not contain sulfur. (No)

3. **Threonine**:
- Chemical structure: C4H9NO3
- Does not contain sulfur. (No)

4. **Cysteine**:
- Chemical structure: C3H7NO2S
- Contains sulfur. (Yes)

5. **Alanine**:
- Chemical structure: C3H7NO2
- Does not contain sulfur. (No)

6. **Tryptophan**:
- Chemical structure: C11H12N2O2
- Does not contain sulfur. (No)

7. **Valine**:
- Chemical structure: C5H11NO2
- Does not contain sulfur. (No)

### Step 3: Count the sulfur-containing amino acids
From the analysis:
- Methionine (contains sulfur)
- Cysteine (contains sulfur)

Thus, there are **2 amino acids** that contain sulfur in their chemical structure.

### Final Answer
The total number of amino acids that contain sulfur is **2**.

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