Question: 138 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 :
(1) \mathrm{C}, \mathrm{B}, \mathrm{D}, \mathrm{A}
(2) \mathrm{B}, \mathrm{D}, \mathrm{A}, \mathrm{C}
(3) \mathrm{B}, \mathrm{C}, \mathrm{D}, \mathrm{A}
(4) \mathrm{C}, \mathrm{A}, \mathrm{B}, \mathrm{D}
Answer: Option (1)
Explanation:
The isolated DNA is then cut at specific sites using restriction enzymes,
which corresponds to step B.
The gene of interest is amplified using PCR to obtain multiple copies, which is step D.
Finally, the recombinant DNA is inserted into a suitable host cell for expression, which is step A.
This sequence is represented by Option (1): C, B, D, A.
Alternatively, in some procedures, cutting of DNA by restriction enzymes is carried out first,
followed by isolation of the desired DNA fragment, then amplification by PCR,
and finally insertion into the host cell.
This sequence corresponds to Option (3): B, C, D, A.
Hence, both Option (1) and Option (3) represent correct sequences of steps involved in the formation of recombinant DNA.