After completing the transformation experiment involving the coding sequence of enzyme n -galactosidase, the recombinant colonies should:

Options

A. give blue colour
B. not given blue colour
C. have active b -galactosidase
D. both (2) and (3)

Answer

To solve the question regarding the color of recombinant colonies after completing the transformation experiment involving the coding sequence of the enzyme n-galactosidase, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Vector Used**: The experiment involves a plasmid vector, specifically the PUC plasmid, which contains the LacZ gene that codes for the enzyme beta-galactosidase (n-galactosidase).

2. **Insertion of Gene of Interest**: During the transformation experiment, the gene of interest (in this case, the coding sequence for n-galactosidase) is ligated into the LacZ gene region of the plasmid. This process creates recombinant DNA.

3. **Insertional Inactivation**: When the gene of interest is inserted into the LacZ gene, it leads to insertional inactivation. This means that the LacZ gene is disrupted, and the beta-galactosidase enzyme is no longer produced.

4. **Blue-White Screening**: The blue-white screening method is used to differentiate between recombinant and non-recombinant colonies. In the presence of X-gal, non-recombinant colonies (which have an intact LacZ gene) will produce the enzyme beta-galactosidase and turn blue. In contrast, recombinant colonies (which have the LacZ gene disrupted) will not produce the enzyme and will appear white.

5. **Conclusion**: Since the recombinant colonies have the LacZ gene inactivated due to the insertion of the gene of interest, they will not produce the blue color. Instead, they will appear white.

### Final Answer:
The recombinant colonies should give a **white color**.

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