Question

Enlist different types of restriction enzymes commonly used in rDNA technology? Write about their role.

Answer 1

There are three types of restriction enzymes:

1. Type I – These enzymes function simultaneously as endonuclease and methylase e.g. EcoK.
2. Type II – These enzymes have separate activities for cleaving and methylation; they are more stable and are used in rDNA technology e.g. EcoRI, BglII; these enzymes cut DNA at specific sites within the palindrome. There are thousands of type II restriction enzymes that are recognized/ discovered.
3. Type III – These enzymes cut DNA at specific non-palindromic sequences e.g. HpaI, MboII.

Role of restriction enzymes:

Restriction enzymes either cut straight across the DNA in the region of palindrome to give blunt ends or cuts producing short, single-stranded projections at each end of DNA to produce, cohesive or sticky ends or staggered ends.