Question

Arrange the following steps which are involved in the process of recombinant DNA technology in correct sequence.
(A) Fragmentation of DNA by restriction endonucleases
(B) Transferring the recombinant DNA into the host
(C) Ligation of desired DNA fragment into a vector
(D) Isolation of DNA
Choose the correct answer from the options given below:

• A. (A), (C), (B), (D)
• B. (B), (D), (C), (A)
• C. (C), (A), (D), (B)
• D. (D), (A), (C), (B)

Hint:

Flowchart of Genetic Engineering:
1. DNA Isolation $\rightarrow$ 2. Restriction Digestion $\rightarrow$ 3. Gel Isolation $\rightarrow$ 4. Ligation into Vector $\rightarrow$ 5. Transformation into Host $\rightarrow$ 6. Culturing in Bioreactors $\rightarrow$ 7. Downstream Processing.

Answer 1

The Correct Option is D

Concept:
Recombinant DNA technology comprises sequential genetic and molecular manipulations aimed at isolating a target gene and producing transgenic organisms or products.

Step 1: Tracing the Core Sequence of rDNA Technology:
1. Isolation of DNA (D): The host and donor cells are lysed enzymatically to release and purify high-molecular-weight genomic DNA free of other macromolecules.
2. Fragmentation of DNA (A): The isolated purified DNA is cleaved into fragments using specific restriction endonucleases, followed by agarose gel electrophoresis to isolate the gene of interest.
3. Ligation into a Vector (C): The isolated gene of interest is ligated into an enzymatically cleaved cloning vector (plasmid/bacteriophage) using the enzyme DNA ligase to construct recombinant DNA.
4. Transferring rDNA into the Host (B): The recombinant vector is introduced into a competent recipient host cell (e.g., bacterial transformation) for multiplication and expression.

Step 2: Formulating the Chronological Sequence:
The correct chronological order of the given steps is:
Isolation of DNA (D) $\rightarrow$ Fragmentation by restriction enzymes (A) $\rightarrow$ Ligation into a vector (C) $\rightarrow$ Transferring rDNA into the host (B).
This corresponds to sequence (D), (A), (C), (B).

Step 3: Final Answer:
Thus, Option (D) is the correct answer.