Final answer:
Exonuclease activity involves removing nucleotides from the ends of DNA, notably for primer removal and DNA repair. Endonuclease activity makes specific cuts within DNA sequences, often utilized by restriction enzymes for molecular cloning and DNA fingerprinting.
Step-by-step explanation:
Differences Between Exonuclease and Endonuclease Activities
The exonuclease activity refers to the enzymatic process where nucleotides are removed from the ends of a DNA molecule. Specifically, exonucleases are involved in removing RNA primers from newly synthesized DNA strands and also have a role in repairing DNA. They work by cleaving nucleotides one at a time from an end (either 5' or 3' end) of the DNA chain.
In contrast, endonuclease activity involves cleaving the phosphodiester bonds within a DNA molecule, but at specific internal sequences. Restriction endonucleases, a type of endonuclease, are known for their precision in cutting DNA at specific nucleotide sequences, which makes them essential tools in molecular biology for cloning and DNA fingerprinting. The cleavage by these endonucleases provides mechanism for defense against invading DNA, such as phage DNA in prokaryotes.
Therefore, while exonucleases remove nucleotides from the ends of DNA, endonucleases make cuts at specific interior locations within the DNA molecule.