Question

Explain the role of restriction endonucleases in recombinant DNA technology. Name the endonucleases that was first discovered.

Answer 1

Hint: A protein which is released by bacteria in order to cut DNA into fragments is restriction endonucleases and it eliminates infecting organisms. This enzyme is found in bacteria.

Complete answer:
First of all, you should know what restriction endonucleases are. Restriction endonucleases is an enzyme which is used to cleave the double stranded DNA into fragments near the recognition sites.
Restriction enzymes are of four types i.e., Type I, II,III and IV. These types differ on the basis of their structure, cleavage sites and recognition sites. For cutting the DNA, all the types of restriction enzymes need to make two cuts i.e., one through each strand of DNA.
The sequences which are determined by restriction enzymes is called Palindromes which is the base sequence that read the same on two strands but in opposite direction, for example,
5' GAATTC 3'
3' CTTAAG 5'
Role of restriction endonuclease:
-This enzyme cuts the DNA very precisely and thus eliminates the infecting organisms.
-It cut double stranded DNA at specific recognition sites.
-This enzyme can recognise specific base sequences on DNA and then it cut each strand at the given place, therefore restriction endonucleases are also called as 'Molecular Scissors'
-It was used to restrict the growth of viruses when it was discovered in bacteria.
-This enzyme is now used in biotechnology and recombinant DNA research.
-It can be isolated from bacterial cells and that is why it is used in laboratories to manipulate the fragments of DNA.
The first endonuclease discovered is Hind II.

Additional Information:
Some enzymes like EcoRI digestion produce sticky ends whereas small restriction enzymes cleavage produces blunt ends.

Note:
This enzyme is used to cleave double stranded DNA sequence into fragments by recognising a specific sequence of nucleotides. It is really important in recombinant DNA technology to cut each strand at specific and there are five types of restriction enzymes. Endonuclease which was discovered first is Hind II.