In competitive inhibition

Options

A. inhibitor resembles the substrate in molecular structure
B. inhibitor binds to allosteric site and block it
C. inhibitor has no effect on active site
D. all correct

Answer

**Step-by-Step Solution:**

1. **Understanding Competitive Inhibition**: Competitive inhibition occurs when an inhibitor competes with the substrate for binding to the active site of an enzyme. This means that the inhibitor has a similar structure to the substrate.

2. **Identifying the Role of the Inhibitor**: In competitive inhibition, the inhibitor resembles the substrate in molecular structure. This allows it to bind to the active site of the enzyme, preventing the actual substrate from binding.

3. **Analyzing the Options**:
- **Option 1**: "The inhibitor resembles the substrate in molecular structure" - This is true as competitive inhibitors mimic the substrate.
- **Option 2**: "Inhibitor binds to allosteric site and blocks it" - This is false for competitive inhibition, as allosteric inhibition involves binding to a different site.
- **Option 3**: "Inhibitor has no effect on the active site" - This is also false, as the inhibitor directly competes with the substrate for the active site.
- **Option 4**: "All are correct" - This is false because not all statements are correct.

4. **Conclusion**: The correct answer is that in competitive inhibition, the inhibitor resembles the substrate in molecular structure.

**Final Answer**: The correct option is: "The inhibitor resembles the substrate in molecular structure."

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