According to Lock and Key Hypothesis

Options

A. Both enzyme and substrate molecules have specific geometrical shapes
B. Only enzymes have a fixed shape
C. Only substrates have a fixed shape
D. Only products have specific shape which is compatible to the enzyme's active site

Answer

### Step-by-Step Solution:

1. **Understanding the Lock and Key Hypothesis**:
- The Lock and Key Hypothesis was proposed by Emil Fischer in 1894. It describes how enzymes and substrates interact based on their specific shapes.

2. **Key Components**:
- Enzymes: Biological catalysts that speed up chemical reactions. They have a specific three-dimensional structure.
- Substrates: The reactants that enzymes act upon. They also have a specific shape that must fit the enzyme.

3. **Active Site**:
- The active site of an enzyme is the region where the substrate binds. It has a unique shape that is complementary to the shape of the substrate.

4. **Formation of Enzyme-Substrate Complex**:
- When the substrate fits into the active site of the enzyme, they form an enzyme-substrate complex. This is akin to a key fitting into a lock.

5. **Specific Geometrical Shapes**:
- According to the Lock and Key Hypothesis, both the enzyme and the substrate have specific geometrical shapes that allow them to fit together perfectly. This means that the shapes do not change during the interaction.

6. **Conclusion**:
- The Lock and Key Hypothesis emphasizes the specificity of enzyme-substrate interactions, where only the correct substrate can fit into the enzyme's active site, similar to how a specific key fits into a lock.