Question

Name the enzyme which is responsible for DNA fragmentation.

Answer 1

Hint: There are certain enzymes present that are capable of breaking the phosphodiester bonds of DNA resulting in the fragmentation of DNA. Such enzymes are known as nucleases which are further divided into endonucleases and endonucleases.

Complete answer:
The DNA is a type of nucleic acid that is made up of the repeating unit nucleotides. These nucleotides are joined together by phosphodiester bonds. If these bonds are broken then DNA will be broken into many tiny fragments. This process is known as DNA fragmentation and it is done through restriction digestion. Restriction digestion takes place by the action of restriction endonucleases which cut the DNA at specific sites. Such cuts can leave the two DNA pieces with blunt or sticky ends. In blunt ends, the edges do not have any unpaired nucleotides whereas in sticky ends unpaired nucleotides are found which have a tendency to stick.
-Restriction enzymes were first isolated from the bacteriophage living inside Escherichia coli.
- The first restriction endonuclease enzyme is known as Hind-II which cuts a DNA sequence at a specific palindromic site.
-Palindrome are words that read the same even after we change the direction of reading. For example - MALAYALAM.
-Such palindromic sequences are known as. Recognition sites of that enzyme.
-Today there are more than 900 restriction enzymes that have been isolated from 230 different strains of bacteria.

Note:
-The cut pieces of DNA after restriction digestion are separated by the process of gel electrophoresis.
-In this electrophoresis process, the DNA pieces are made to move across an electric field. The DNA pieces move towards the positive anode as they are negatively charged.
-The smaller DNA pieces move the farthest distance as compared to bigger sized pieces.