Question

Restriction enzymes are used in genetic engineering because

• A. They can join different DNA fragments
• B. They are proteolytic enzymes which can degrade harmful enzymes
• C. They can cleave DNA at a specific target
  
• D. They are nucleases that cut DNA at variable sites

Answer 1

The correct option is C They can cleave DNA at a specific target


Genetic engineering
Genetic engineering is a technique in which genetic material such as DNA or RNA is modified and introduced into the host. Thus, the phenotype of the host organisms gets changed by the expression of this modified or altered DNA.

Restriction enzymes
Restriction endonucleases are the enzymes which cleave the DNA by digesting phosphodiester bonds at the specific sequences within the DNA. Examples include EcoRI.

The cutting of DNA provides space for the insertion of foreign DNA into the vector DNA to form rDNA. Hence they are used in genetic engineering.

DNA ligase
DNA ligase is the enzyme that creates the phosphodiester bond between the nucleotides of DNA fragments and joins them together. It helps in the joining of vectors and DNA of interests in genetic engineering to create recombinant DNA molecules.

Protease
Proteases are enzymes that digest polypeptides into amino acids. Harmful proteins are hence degraded by proteases.

Final answer
b. They can cleave DNA at a specific target.