Question

The basic scheme of the essential steps involved in the process of recombinant DNA technology is summarised below in the form of a flow diagram. Study the given flow diagram and answer the questions that follow.

(a) What is the technical term used for Step 4 in the above process?
(b) Which of the given two combinations of restriction enzyme should be used in Step 1? Justify your answer. 
(i) EcoR I to cut the plasmid and Hind III to cut the alien DNA. 
(ii) EcoR I to cut both the plasmid and alien DNA.

Hint:

Cloning is the term for replicating recombinant DNA. Always use the same restriction enzyme on both vector and insert to produce compatible sticky ends.

Answer 1

(a) Step 1: Step 4 is the process of generating numerous copies of recombinant DNA.
Step 2: This process is technically termed cloning.
Step 3: Cloning facilitates the amplification of the desired gene within the host cell. 
(b) Step 1: Ligation of both vector and foreign DNA necessitates compatible ends. 
Step 2: If distinct enzymes (e.g., EcoR I and Hind III) are employed, the resulting ends will be incompatible, preventing successful ligation. 
Step 3: Consequently, the appropriate choice is (ii): Utilizing EcoR I to cleave both the plasmid and alien DNA. 
Step 4: The use of an identical restriction enzyme guarantees that both DNA fragments possess complementary sticky ends, enabling facile joining.