Question

The enzymes which are commonly used in genetic engineering are
a) Endonuclease and ligase
b) Restriction endonuclease and polymerase
c) Ligase and polymerase
d) Restriction endonuclease and ligase

Answer 1

Genetic engineering is a technology in which the non desired genes are replaced by the desired genes by either inserting recombinant DNA sequence or by controlled breeding. Humans have used this technology to only develop desired genes where the quality of the breed is enhanced. Some of the examples are the green revolution and the white revolution.

Complete answer:
The process involved in genetic engineering includes isolation of gene of interest, cutting of DNA using restriction endonuclease, joining of vector and target DNA, and introduction of recombinant DNA into the host cell. The cloning vectors are used as cloning vectors can be easily copied and then can be transferred from one place to another. The vectors used are either a bacterial plasmid or extracted from the plasmid of yeast. Now the target DNA and the cloning DNA are cut using the restriction enzymes. The restriction enzymes usually cut straight ends or sometimes cut and give staggering ends which are also known as the sticky ends. The sequence cut is usually of small bases consisting of 4-8 bp long. When both the DNA's are cut then they are joined together using the ligase enzyme. Two different types of DNA combine with DNA ligase to form the recombinant DNA. After recombinant DNA is formed, this DNA is then transferred to the host cell.
So, the answer is 'd) Restriction endonuclease and ligase'.

Note: The recombinant DNA when stable is inserted into the host cell. There it multiplies and produces the desired quality needed. There are different ways of transporting the DNA into the host depending upon their machinery of the cell. Transformation, electroporation, and shotgun cloning are commonly used methods.