How does a restriction nuclease function? Explain. (2)
Restriction nucleases are of two types-endonucleases cut at specific positions within a DNA. Exonucleases remove nucleotides from the ends of DNA.
Each restriction endonuclease functions by inspecting the length of a DNA sequence. It recognises a specific palindromic nucleotide sequence GAATTC is present in the DNA.
Restriction enzyme cuts the strand of DNA a little away from the centre of the palindrome sites, but between the two bases on the opposite strands. This leaves single stranded portions at the ends. There are overhanging strands called sticky ends on each strand. This stickiness facilitates the function of ligase enzyme. (2)