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Class 12th Biology 2013 Set1 Delhi Board Paper Solution

Question 15

Expand the following and mention one application of each:
(i) PCR
(ii) ELISA
OR (a) Mention the difference in the mode of action of exonuclease and endonuclease.
(b) How does restriction endonuclease function?

(i) PCR - Polymerase Chain Reaction
(ii) ELISA - Enzyme linked Immuno sorbent Assay.
(a) Exonuclease - cuts the DNA at free ends.
Endonuclease - cuts within DNA segment
(b) Resticriction endonuclease, : cuts within the DNA, at specific sites called pallindromic sites.
e.g. Eco R1 cuts the DNA at following pallindromic sequences.
        5' G A A       T T C   3' 
        3' C T T       A A G 5'