Restriction enzymes are found in bacteria (and other prokaryotes)… - Vidyadip

Question

Restriction enzymes are found in bacteria (and other prokaryotes). They recognize and bind to specific sequences of DNA, called restriction sites. Each restriction enzyme recognizes just one or a few restriction sites.
When it finds its target sequence, a restriction enzyme will make a double-stranded cut in the DNA molecule.
i. Write the palindromic nucleotide sequence for the following DNA segment.
5'-GAATTC-3'
ii. Name the restriction endonuclease that recognises this sequence.
iii. How are sticky ends produced? Mention their role.

✓

Answer

i. Palindromic sequence for
5'-GAATTC-3'
3'-CTTAAG-5'
ii. Restriction endonuclease Eco RI recognises the above palindromic sequence.
iii. Sticky ends on DNA are formed by the action of enzymes restriction endonucleases. These enzymes cut the strand of DNA a little away from the centre of the palindrome sequence between the same two bases on both the strands. This results in single- stranded stretches on both the complementary strands at their ends. These overhanging stretches are called sticky ends as they form hydrogen bonds with the complementary basepair sequences.
Role of the sticky ends -These sticky ends produced from hydrogen bonds with their complementary cut counterparts. This stickiness of the ends facilitates the action of the enzyme DNA ligase.

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