NEETZoologyBiotechnology - Principles and Processes
Which of the following statements correctly describes the action of the restriction enzyme EcoRI on its recognition sequence?
Options
- AIt breaks phosphodiester bonds between Guanine and Adenine residues on both the DNA strands.
- BIt breaks hydrogen bonds between the complementary bases to separate the two DNA strands.
- CIt cuts the DNA exactly at the centre of the palindromic sequence to produce blunt ends.
- DIt breaks phosphodiester bonds between Adenine and Thymine residues on both the DNA strands.
Correct answer
A. It breaks phosphodiester bonds between Guanine and Adenine residues on both the DNA strands.
Step-by-step solution
The restriction enzyme EcoRI recognizes the palindromic sequence GAATTC. It cuts the DNA a little away from the centre of the palindrome sites, specifically between the bases Guanine (G) and Adenine (A) on both the opposite strands. Restriction endonucleases function by cutting the sugar-phosphate backbone of DNA, which means they break phosphodiester bonds, not hydrogen bonds. Thus, EcoRI breaks phosphodiester bonds between G and A residues on both strands, leaving single-stranded overhanging stretches known as st