When the addition of foreign DNA is made in the coding sequence of `beta`-galactosidase in Puc19 , this results in

Options

A. Direct DNA injection
B. Transfection
C. Insertional inactivation
D. Transformation

Answer

To solve the question regarding the addition of foreign DNA in the coding sequence of beta-galactosidase in the PUC19 plasmid, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of PUC19**:
- PUC19 is a plasmid vector that contains several important components: an ampicillin resistance gene, an origin of replication, and a coding sequence for beta-galactosidase.

2. **Identify the Role of Beta-Galactosidase**:
- Beta-galactosidase is an enzyme that, when produced, can hydrolyze X-gal (a chromogenic substrate) to produce a blue color. This blue color indicates the presence of functional beta-galactosidase.

3. **Insertion of Foreign DNA**:
- When foreign DNA is inserted into the coding sequence of beta-galactosidase, it disrupts the normal function of the gene. This means that the beta-galactosidase enzyme will not be produced anymore.

4. **Consequences of Insertion**:
- Since beta-galactosidase is not produced due to the insertion of foreign DNA, the reaction with X-gal will not occur. As a result, there will be no blue colonies formed on the medium.

5. **Define the Process**:
- The process by which the insertion of foreign DNA leads to the inactivation of the beta-galactosidase gene is known as "insertional inactivation." This term refers to the loss of function of a gene due to the insertion of additional DNA.

6. **Conclusion**:
- Therefore, the result of inserting foreign DNA into the coding sequence of beta-galactosidase in PUC19 is the phenomenon known as insertional inactivation.

### Final Answer:
The addition of foreign DNA in the coding sequence of beta-galactosidase in PUC19 results in **insertional inactivation**.

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