Number of structural genes in tryptophan operon is

Options

A. 3
B. 4
C. 5
D. 6

Answer

To determine the number of structural genes in the tryptophan operon (trp operon), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Tryptophan Operon**: The trp operon is a group of genes responsible for the biosynthesis of the amino acid tryptophan in bacteria. It is a classic example of gene regulation.

**Hint**: Familiarize yourself with the basic concept of operons and their role in bacterial gene regulation.

2. **Identify the Components of the Tryptophan Operon**: The trp operon consists of several components, including a promoter, operator, regulatory genes, and structural genes.

**Hint**: Remember the key components of operons: regulatory sequences (promoter, operator) and structural genes.

3. **Count the Structural Genes**: The trp operon contains five structural genes. These genes are:
- trpE
- trpD
- trpC
- trpB
- trpA

**Hint**: Make a list of the structural genes to ensure you count them accurately.

4. **Conclusion**: Since we have identified five structural genes in the trp operon, we can conclude that the number of structural genes in the tryptophan operon is **5**.

**Hint**: Verify your answer by recalling the function of each structural gene in tryptophan synthesis.

### Final Answer:
The number of structural genes in the tryptophan operon is **5**.