(a) PCR
(b) Restriction enzymes and DNA
(c) Chitinase
Solution 11:
(a) PCR: The polymerase chain reaction (PCR) is an in vitro molecular biology method that combines enzymatic amplification of a single DNA strand and creating millions of copies of the specified DNA sequence in just a few hours (about 2 hours).
PCR consists of three steps:
(i) Denaturing (at 96°C) the double-stranded DNA into single-stranded DNA.
(ii) Annealing of the primer (at 55-65 oC) to ssDNA (single standard).
(iii) Taq DNA polymerase, an enzyme isolated from Thermus aquaticus, synthesized new strands (at 72 oC).
An amplified gene is used to clone the desired gene.
Advantage – Higher productivity, higher efficiency, reduced error proneness, and fewer human errors, cyclic and automated.
(b) Restriction enzymes and DNA – Restriction enzymes cleave DNA by cleaving a specific sequence of bases known as the recognition site, where the restriction enzyme cleaves the DNA strands.
(i) It prevents foreign DNA from entering normal cells by digesting it at various recognition sites. Sites of recognition are palindromic.
(ii) Both endonucleases and exonucleases are present.
(iii) They produce sticky endings. There is a difference between the recognition site and the cleavage site. The restriction enzymes that bacteria produce are therefore thought to serve as a mechanism for defending themselves against viral attacks and removing viral sequences that interfere with their survival.
(c) Chitinase is an enzyme that breaks down the glycosidic bonds in chitin present in fungi and the exoskeleton of certain arthropods and worms to facilitate their digestion or transformation.
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