Question 67 of 83
Q.Match the following :
(1) Exonuclease
(2) Endonuclease
(3) Alkaline Phosphatase
(4) Ligase
(i) add or remove phosphate
(ii) binding the DNA fragments
(iii) cut the DNA at terminus
(iv) cut the DNA at middle
(a) (1)-(i), (2)-(iii), (3)-(ii), (4)-(iv)
(b) (1)-(i), (2)-(ii), (3)-(iii), (4)-(iv)
(c) (1)-(iii), (2)-(iv), (3)-(i), (4)-(ii)
(d) (1)-(iii), (2)-(iv), (3)-(ii), (4)-(i)
Puducherry TnboardTamil Nadu HSC (DGE) Board 2023MCQ· 1mImportance★★★★★
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Start your 14-day free trial to unlock the full solution →Exonuclease cuts DNA at the terminus, endonuclease cuts it in the middle, alkaline phosphatase adds/removes a phosphate group, and ligase joins DNA fragments -- matching to (c).
Working
These four enzymes are all classic tools of recombinant DNA technology, each with a distinct site and mode of action on a DNA molecule:
- Exonuclease -- removes nucleotides progressively starting from the free end (terminus) of a DNA strand, either from the 5' or 3' end. So (1) matches (iii) "cut the DNA at terminus".
- Endonuclease -- recognises a specific internal sequence and cleaves the DNA strand in the middle of the molecule, not at an end. Restriction endonucleases (e.g. EcoRI) are the best-known example. So (2) matches (iv) "cut the DNA at middle".
- Alkaline phosphatase -- catalyses the removal (or, in reverse reactions, transfer) of a terminal 5'-phosphate group from DNA, commonly used to prevent unwanted self-ligation of a vector. So (3) matches (i) "add or remove phosphate". …
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