Question

An enzyme catalysing the removal of nucleotides from the ends of $DNA$ is

• A. endonuclease
• B. exonuclease
• C. $DNA$ ligase
• D. Hind II

Answer 1

Answer: (B)

Exonucleases remove nucleotides from the terminal ends (either $5^{\prime }$ or $3^{\prime }$) of $DNA$ of one strand of duplex. Endonucleases make cut at specific position within the $DNA$. $DNA$ ligases are known as joining or sealing enzymes. Ligases form phosphodiester bonds between adjacent nucleosides and covalently link two individual fragments of $DNA$. Hind II is restriction endonuclease. It cuts the $DNA$ and produces blunt ends.