Which of the following enzymes makes cuts at specific positions within the DNA?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Endonuclease
Nucleases are enzymes that break DNA. They are of two kinds. Exonucleases remove nucleotides from the ends of the DNA, while endonucleases make cuts at specific positions within the DNA. Restriction endonucleases belong to the second kind.
Option (1) DNA ligase — Incorrect. DNA ligase does not cut DNA. It acts on cut DNA molecules and joins their ends.
Option (2) Exonuclease — Incorrect. Exonucleases work only at the ends of the DNA, removing nucleotides from there.
Option (3) Endonuclease — Correct. Endonucleases cut DNA at specific positions within the molecule.
Option (4) Polymerases — Incorrect. DNA polymerases build DNA by adding nucleotides on a template. They do not cut DNA.
NCERT Extract:
Restriction Enzymes – “… 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.”