How do exonucleases function in nucleic acid digestion?

Exonucleases play a crucial role in nucleic acid digestion by cleaving nucleotides from the ends of a nucleic acid chain. They operate specifically at the free ends of DNA or RNA molecules, which allows for the removal of nucleotides one at a time. This characteristic distinguishes them from other enzymes like endonucleases, which cut the nucleic acid strand at sites within the molecule rather than just at the ends.

By starting digestion at a free end, exonucleases enable processes such as DNA repair, replication, and degradation, which are essential for maintaining cellular functions and overall genomic integrity. This mechanism is fundamental to various biological processes where the precise control of nucleic acid length and composition is necessary.

Other options do not accurately represent how exonucleases work. They do not start digestion in the middle of the nucleic acid molecule nor do they require specific base pair sequences for function. While breaking hydrogen bonds is a part of the overall processes involved in nucleic acid interactions, it is not the specific mode of action that characterizes exonucleases. Their primary function is characterized by their ability to digest nucleic acids from the ends.