Restriction enzymes belong to a larger class of enzymes called nucleases. These are of two kinds; exonucleases and endonucleases. Exonucleases remove nucleotides from the ends of the DNA whereas, endonucleases make cuts at specific positions within the DNA. Each restriction endonuclease functions by ‘inspecting’ the length of a DNA sequence. Once it finds its specific recognition sequence, it will bind to the DNA and cut each of the two strands of the double helix at specific points in their sugar-phosphate backbones. Each restriction endonuclease recognises a specific nucleotide sequences in the DNA.
Which restriction enzymes is used in the above process?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → EcoR I
The figure shows a cut between G and A in the sequence GAATTC, leaving sticky ends: the action of EcoRI.
Option (2) EcoR I — Correct. The figure shows the sticky ends made by cutting at the sequence GAATTC. This sequence is the recognition site of EcoR I, which cuts between G and A on both strands.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.