Explain briefly:
(a) PCR
(b) Restriction enzymes and DNA
( c) Chitinase

Explanation

(i) PCR: PCR stands for polymerase Chain Reaction. In this reaction multiple copies of the gene ( or DNA ) of interest is synthesised vitro in, using sets of primers and the enzyme Taq DNA Polymerase.
(ii) Restriction Enzymes and DNA: these are the enzymes which restrict the growth of bacteriophages. These enzymes are present in many bacteria where they function as a part of their defence mechanism called Restriction Modification System. Restriction enzymes are of two types:
(a) Restriction endonuclease cuts DNA into pieces.
(b) Modification enzyme adds methyl group to DNA.
(iii) Chitinase: it is an enzyme which breaks down the chitinous substance present in the wall of fungi.