Question

How do exonucleases differ fundamentally from endonucleases in their enzymatic site of action?

Options

• Exonucleases remove nucleotides one by one from the free ends of DNA, whereas endonucleases cleave within the DNA strand at internal positions

• Exonucleases synthesize terminal primers, whereas endonucleases ligate internal breaks

• Exonucleases methylate free ends of DNA, whereas endonucleases cleave internal methylated bases

• Exonucleases cleave internal phosphodiester bonds, whereas endonucleases cut only single-stranded RNA ends

Answer 1

Nucleases break nucleic acids; exonucleases act at the ends of DNA to remove bases one by one from free ends, whereas endonucleases make cuts internally within the DNA strand.