Question

Main steps in the formation of Recombinant DNA are given below. Arrange these steps in a correct sequence.
A. Insertion of recombinant DNA into the host cell
B. Cutting of DNA at specific location by restriction enzyme
C. Isolation of desired DNA fragment
D. Amplification of gene of interest using PCR
Choose the correct answer from the options given below:

• A. C, A, B, D
• B. C, B, D, A
• C. B, D, A, C
• D. B, C, D, A

Answer 1

The Correct Option is B

The formation of Recombinant DNA involves a sequence of critical steps. Below is the correct sequence along with explanations for each step:

1. Isolation of desired DNA fragment (C): The process begins by identifying and isolating the specific DNA fragment that contains the gene of interest. This involves extracting DNA from the cells.
2. Cutting of DNA at specific location by restriction enzyme (B): Enzymes known as restriction endonucleases are used to cut the DNA at specific sequences. These enzymes are like molecular scissors, allowing the precise cutting of DNA and enabling the isolation of the desired fragment.
3. Amplification of gene of interest using PCR (D): Polymerase Chain Reaction (PCR) is then used to amplify the gene of interest. This is a method to create multiple copies of a specific DNA fragment, making it easier to work with large quantities of the gene.
4. Insertion of recombinant DNA into the host cell (A): Finally, the recombinant DNA is inserted into a host cell. This step involves introducing the manipulated DNA into a new organism’s DNA to study its expression or to produce proteins.

Thus, the correct sequence of steps in the formation of recombinant DNA is: C, B, D, A.

Answer 2

The correct option is (B): C,B,D, A
Correct sequences in the formation of recombinant DNA are as follows:
1. Cutting of DNA at a specific location by restriction enzyme
2. Isolation of desired DNA fragment
3. Amplification of genes of interest using PCR
4. Insertion of recombinant DNA into the host cell
The first step in recombinant DNA technology is the isolation of the desired gene or DNA fragment in its pure state. It is necessary to reproduce a DNA sequence that carries genetic information. To isolate the desired DNA fragment it is necessary to first obtain the DNA from whole tissue or cell cultures and then purify the DNA from macromolecules like lipids, proteins etc.
The second step involves the cutting of DNA at a particular position, restriction enzymes play a vital role in recognizing the DNA sequence and cutting the DNA at desired location.
The third step includes the amplification of genes of interest by polymerase chain reaction to produce multiple copies of a single DNA fragment.
After this, the joining of the vector and the cut fragment of DNA is done by an enzyme called ligase and the process is called ligation.
Finally, the recombinant DNA is inserted into a suitable vector. A vector is a carrier responsible for carrying the gene of interest into a given cell where it is replicated during cell division.
Therefore, option (B) is correct.