Given below are the steps carried out to construct a recombinant DNA. Which one of the following gives the correct sequence of these steps ?

(i) Isolation of genetic material

(ii) Insertion of recombinant DNA in the host cell / organism

(iii) Obtaining the foreign gene product

(iv) Amplification of gene of interest

(v) Downstream processing

The correct sequence of steps for constructing a recombinant DNA and obtaining the desired product is (i) → (iv) → (ii) → (iii) → (v).

Here is the step-by-step educational breakdown of the process of recombinant DNA technology:

1. (i) Isolation of genetic material:
Before any manipulation can begin, the donor DNA (genetic material containing the gene of interest) must be isolated in its pure form, free from other macromolecules like proteins, RNA, lipids, etc.

2. (iv) Amplification of gene of interest:
Once isolated, the specific gene of interest is amplified using Polymerase Chain Reaction (PCR) to obtain multiple copies of the gene. In actual experimental workflows, the gene is also cut using restriction enzymes and ligated into a vector, but amplification represents the next logical phase in preparing the DNA for insertion.

3. (ii) Insertion of recombinant DNA in the host cell / organism:
The construct containing the gene of interest (recombinant DNA) is then introduced into a suitable recipient host cell or organism (e.g., Escherichia coli) through transformation techniques.

4. (iii) Obtaining the foreign gene product:
The transformed host cells are cultured in appropriate media at a large scale (often in bioreactors) to express the transgene and produce the desired protein/foreign gene product.

5. (v) Downstream processing:
The final stage involves the separation and purification of the expressed product, followed by quality control testing and formulation before the product is ready for commercial or clinical use.