Q) Explain the role of restriction enzymes in the synthesis of a recombinant molecule
Main points | |
Key idea: | What are restriction enzymes (RE) |
· Endonucleases that hydrolyze phosphodiester bonds to produce restriction fragments | |
Key idea: | Specificity |
· Specific, each endonuclease recognizes a specific base seq before cutting DNA. · Recognition seq (often palindromic) called restriction site | |
Key idea: | Significance of restriction fragments |
· 2 types of restriction fragments may be produced – ‘blunt-ends’ fragments & ‘sticky-ends’ fragments · ‘Sticky-ends’ fragments particularly useful for joining diff DNA which are cut w the same RE · Reason: ‘sticky ends’ of one restriction fragment consists of unpaired overhangs which can base pair w other complementary unpaired overhangs of another restriction fragment to produce recombinant DNA | |
Comments: (i) Visualize the answer with the aid of a labelled diagram. (ii) Verbalize the answer + write down the main points w/o referring to the answer (use abbreviations) (iii) Read again within the next 24h & once more within 72h (do not spend more than 10min) (iv) Palindromic sequence of recognition site of restriction enzyme refers to a DNA locus where the 5’ to 3’ base sequence on each DNA strand is identical. An example : 5’ GAATTC 3’ 3’ CTTAAG 5’ | |
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