Sulpha drugs / sulphanilamides kill bacteria by inhibiting synthesis of folic acid from para-aminobenzoic acid. This type of control of bacterial pathogens is

Options

A. Noncompetitive inhibition
B. Allosteric inhibition
C. Competitive inhibition
D. Negative feed back

Answer

**Step-by-Step Solution:**

1. **Understanding the Role of Folic Acid in Bacteria:**
- Folic acid (Vitamin B9) is essential for bacterial growth and reproduction. Bacteria synthesize folic acid from para-aminobenzoic acid (PABA).

**Hint:** Remember that folic acid is crucial for DNA synthesis and cellular functions in bacteria.

2. **Mechanism of Action of Sulfa Drugs:**
- Sulfa drugs, or sulfanilamides, mimic PABA and compete with it for the active site of the enzyme folic acid synthetase. When sulfa drugs bind to this enzyme, they inhibit its activity.

**Hint:** Think of sulfa drugs as impostors that prevent the real substrate (PABA) from binding to the enzyme.

3. **Identifying the Type of Inhibition:**
- The competition between sulfa drugs and PABA for the active site of the enzyme indicates that this is a case of competitive inhibition. In competitive inhibition, the inhibitor competes directly with the substrate for the active site.

**Hint:** Recall that in competitive inhibition, the presence of the inhibitor can be overcome by increasing the concentration of the substrate.

4. **Consequences of Competitive Inhibition:**
- When sulfa drugs occupy the active site, the enzyme cannot convert PABA into folic acid. This leads to a deficiency of folic acid, thereby hindering bacterial growth and reproduction, ultimately resulting in bacterial death.

**Hint:** Consider how the lack of folic acid affects the overall health and reproduction of bacteria.

5. **Conclusion:**
- Therefore, the type of control exerted by sulfa drugs on bacterial pathogens is classified as **competitive inhibition**.

**Hint:** Remember that competitive inhibition is characterized by the direct competition for the active site, which is the key feature distinguishing it from other types of inhibition.

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