Question

Explain the difference between exonuclease and endonuclease enzymes.

Hint:

Exonucleases and endonucleases play critical roles in DNA repair and modification by cleaving nucleotides in different ways.

Answer 1

Step 1: Exonuclease.
Exonucleases are enzymes that remove nucleotides from the ends of a DNA strand. They can remove one nucleotide at a time from either the 3' or 5' end of a DNA strand. Exonucleases are important for DNA repair and replication processes.
Step 2: Endonuclease.
Endonucleases are enzymes that cleave the phosphodiester bond within a DNA molecule, making cuts within the DNA strand. These enzymes are important in DNA repair, recombination, and restriction digestion.
Step 3: Key Differences.
- Exonuclease: Removes nucleotides from the ends of the DNA strand. - Endonuclease: Cuts DNA at specific internal sites within the strand.
Step 4: Conclusion.
Thus, exonucleases and endonucleases differ in their action on the DNA strand, with exonucleases working at the ends and endonucleases making internal cuts.
Final Answer: \[ \boxed{\text{Exonucleases remove nucleotides from the ends of DNA, while endonucleases cut at internal sites.}} \]