Colony hybridization is used in

Options

A. Isolation of desired gene
B. Insertional inactivation
C. Cutting of DNA at specific loaction
D. Seleciton of transformed cells

Answer

**Step-by-Step Solution:**

1. **Understanding Colony Hybridization**: Colony hybridization is a technique used to identify specific colonies of microorganisms that contain a desired DNA sequence. This method is particularly useful in genetic engineering and molecular biology.

2. **Setting Up the Experiment**: In a petri dish, a culture of bacteria is grown, leading to the formation of distinct colonies. Each colony originates from a single bacterium and represents a clone of that bacterium.

3. **Transferring Colonies**: A nitrocellulose membrane is placed on top of the bacterial colonies. The membrane is pressed down gently, allowing the colonies to transfer their DNA onto the membrane in the same spatial arrangement as they were on the petri dish.

4. **Cell Lysis and DNA Denaturation**: The next step involves lysing the cells to release their DNA. This is followed by denaturing the DNA, which means separating the double-stranded DNA into single strands.

5. **Using a Radiolabeled Probe**: A radiolabeled probe, which is a short sequence of nucleotides complementary to the desired gene, is applied to the membrane. This probe will hybridize (bind) to any complementary DNA present on the membrane.

6. **Incubation and Visualization**: After incubation, the membrane is washed to remove any unbound probes. The remaining bound probes can be visualized using autoradiography, which involves exposing the membrane to X-ray film or a similar medium. The areas where the probe has bound will appear as spots on the film.

7. **Identifying Desired Colonies**: By examining the autoradiograph, researchers can identify which colonies contain the desired gene based on the presence of spots corresponding to the radiolabeled probes.

8. **Applications of Colony Hybridization**: The primary applications of colony hybridization include:
- Isolation of desired genes.
- Selection of transformed cells that have taken up recombinant DNA.
- Insertional inactivation to confirm successful cloning.
- Cutting of DNA at specific locations for further genetic manipulation.

**Final Answer**: Colony hybridization is used for the isolation of desired genes and the selection of transformed cells in genetic engineering.

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