Select the correct statement from the following :

Options

A. Gel electrophoresis is used for amplification of a DNA segment.
B. The polymerase enzyme joins the gene of interest and the vector DNA.
C. Restriction enzyme digestions are performed by incubating purified DNA molecules with the restriction enzymes of optimum conditions.
D. PCR is used for isolation and separation of gene of interest.

Answer

To solve the question of selecting the correct statement from the given options, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Analyze the First Statement:**
- The statement claims that "Gel electrophoresis is used for amplification of our DNA segment."
- **Evaluation:** Gel electrophoresis is a technique primarily used for the separation and isolation of DNA fragments based on size, not for amplification. Amplification of DNA segments is achieved through the Polymerase Chain Reaction (PCR).
- **Conclusion:** This statement is **incorrect**.

2. **Analyze the Second Statement:**
- The statement claims that "The polymerase enzyme joins the gene of interest to the vector DNA."
- **Evaluation:** The enzyme responsible for joining DNA fragments, such as a gene of interest to a vector, is ligase, not polymerase. Polymerases are primarily involved in DNA synthesis.
- **Conclusion:** This statement is **incorrect**.

3. **Analyze the Third Statement:**
- The statement claims that "The other restriction enzymes, digestions are performed by incubating purified DNA molecules with the restriction enzymes of optimum conditions."
- **Evaluation:** This statement accurately describes the process of restriction enzyme digestion. Restriction enzymes cut DNA at specific recognition sites, and the digestion process involves incubating purified DNA with these enzymes under optimal conditions.
- **Conclusion:** This statement is **correct**.

4. **Analyze the Fourth Statement:**
- The statement claims that "PCR is used for isolation and separation of gene of interest."
- **Evaluation:** PCR is used for the amplification of DNA, not for isolation or separation. Gel electrophoresis is the technique used for the separation of DNA fragments after amplification.
- **Conclusion:** This statement is **incorrect**.

### Final Conclusion:
The only correct statement among the provided options is the **third statement** regarding restriction enzyme digestion.