The mode of action of penicillin on bacterial growth is by inhibition of :

Options

A. Peptidoglycan synthesis
B. Protein synthesis
C. mRNA synthesis
D. Paramylum synthesis

Answer

To solve the question regarding the mode of action of penicillin on bacterial growth, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks about the specific mechanism through which penicillin inhibits bacterial growth.

2. **Identify the Options**: The options provided are:
- A) Peptidoglycan synthesis
- B) Protein synthesis
- C) mRNA synthesis
- D) Paramylum synthesis

3. **Analyze Each Option**:
- **Option A: Peptidoglycan synthesis**: Penicillin is known to target the bacterial cell wall, which is primarily composed of peptidoglycan. By inhibiting the synthesis of peptidoglycan, penicillin weakens the cell wall, leading to cell lysis and death of the bacteria. This option is correct.
- **Option B: Protein synthesis**: Penicillin does not inhibit protein synthesis directly. Other antibiotics, such as tetracyclines and aminoglycosides, are known for this mode of action. Therefore, this option is incorrect.
- **Option C: mRNA synthesis**: Penicillin does not interfere with mRNA synthesis. This process is more relevant to other types of antibiotics, such as rifampicin. Thus, this option is also incorrect.
- **Option D: Paramylum synthesis**: Paramylum is a polysaccharide found in certain algae and is not related to bacterial growth or the action of penicillin. Therefore, this option is incorrect.

4. **Conclusion**: After analyzing all the options, the correct answer is **A) Peptidoglycan synthesis**. Penicillin inhibits the synthesis of peptidoglycan, which is crucial for bacterial cell wall integrity.

### Final Answer:
The mode of action of penicillin on bacterial growth is by inhibition of **peptidoglycan synthesis**.

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