For making GMO , which of the following step is mandatory ?

Options

A. Identification of DNA with desirable gene.
B. Introduction of identified DNA into the host.
C. Maintenance of introduced DNA in the host and transfer of the DNA to its progeny.
D. All the above

Answer

To determine which step is mandatory for making a Genetically Modified Organism (GMO), we can break down the process into several key steps:

### Step-by-Step Solution:

1. **Identify the Desirable DNA**:
- The first step in creating a GMO is to identify the DNA that contains the desirable gene. This gene is the one that will confer the desired traits to the organism.

**Hint**: Think about why it's important to know what gene you want to insert before you can modify an organism.

2. **Isolation of the Identified DNA**:
- Once the desirable DNA is identified, the next step is to isolate this DNA. This involves extracting the DNA from the source organism where it is found.

**Hint**: Consider how you would separate a specific ingredient from a mixture in cooking.

3. **Introduction of the Isolated DNA into the Host**:
- After isolation, the next crucial step is to introduce or insert the isolated DNA into the host organism’s cells. This is often done using various techniques such as transformation, transfection, or electroporation.

**Hint**: Think about how you would introduce a new ingredient into a recipe to change the final dish.

4. **Growth of the Recombinant Vector in the Host**:
- Following the introduction of the DNA, it is essential for the recombinant DNA to grow and replicate within the host organism. This ensures that the new traits are expressed.

**Hint**: Imagine how a new plant variety grows after being planted in soil.

5. **Maintenance of Introduced DNA in the Host and Transfer to Progeny**:
- Finally, the introduced DNA must be maintained in the host and passed on to its progeny during reproduction. This ensures that the desirable traits are inherited by future generations.

**Hint**: Consider how family recipes are passed down through generations.

### Conclusion:
All of the steps mentioned above are mandatory for the preparation of a GMO. Therefore, the correct answer is **"All of the above"**.

### Final Answer:
**All of the above steps are mandatory for making a GMO.**