Question

How the restriction endonuclease cut the recognition sequence?

Answer 1

A restriction enzyme or restriction endonuclease is an enzyme that cleaves DNA into fragments at or near specific recognition sites within the molecule known as restriction sites.[1][2][3] Restrictions enzymes are one class of the broader endonuclease group of enzymes. Restriction enzymes are commonly classified into five types, which differ in their structure and whether they cut their DNA substrate at their recognition site, or if the recognition and cleavage sites are separate from one another. To cut DNA, all restriction enzymes make two incisions, once through each sugar-phosphate backbone (i.e. each strand) of the DNA double helix.
These enzymes are found in bacteria and archaea and provide a defence mechanism against invading viruses.[4][5] Inside a prokaryote, the restriction enzymes selectively cut up foreign DNA in a process called restriction digestion; meanwhile, host DNA is protected by a modification enzyme (a methyltransferase) that modifies the prokaryotic DNA and blocks cleavage. Together, these two processes form the restriction modification system.[6]

Answer 2

Restriction Endonuclease

》Restriction Endonuclease belongs to a class of enzymes called nucleases which cuts the DNA strands at the ends.

》There are some specific recognition sites where the restriction enzyme works.

》These recognition sites are known as palindromic sequence.

》The entire strand of the DNA is suspected by the enzyme and when it finds its recognition site, it binds to the DNA and cuts the two opposite strands.

》It cuts the DNA strand not at the centre but a few distance away from the palindromic sequence.

》Overhanging stretches called Sticky Ends are formed as the ezyme cuts the DNA between the same base pairs on the opposite strands.