Why are enzymes like protease useful in DNA isolation?

Correct answer: To remove protein impurities

Proteases are enzymes that break proteins into smaller peptides and amino acids. During DNA isolation, proteins from cells can remain mixed with the DNA, including structural proteins and DNA-associated proteins. Treating the sample with a protease digests these unwanted proteins, making it easier to separate and purify the DNA. Removing protein contamination is important because leftover proteins can interfere with later steps such as restriction digestion, amplification, or other analysis.

Thus option C is correct: protease-like enzymes help remove protein impurities. They do not color DNA, transform a cell into a plant, or freeze water. In a typical isolation procedure, protease treatment is combined with cell disruption and other purification steps. The enzyme acts on proteins, while the DNA is retained for collection and subsequent experiments. This is why proteases improve the quality of the isolated DNA.