What is the purpose of adding RNase to a patient sample during genomic DNA isolation?

• A. RNase serves as an enzymatic tag on DNA probes.
• B. RNase will remove excess collagen from the patient sample.
• C. RNase will transport amino acids to the ribosome, where the peptide chain elongates.
• D. RNase digests RNA in the patient sample that could co-purify with genomic DNA.

Answer: (D)

During genomic DNA isolation, RNA from the sample can co-purify with the DNA and contaminate the preparation. Adding RNase targets and digests this RNA, breaking it down into nucleotides that are then removed in subsequent cleanup steps. This leaves the genomic DNA intact and results in a purer DNA preparation, which improves accuracy of DNA quantification and reliability of downstream applications like PCR and sequencing. The other options describe roles outside DNA purification, such as tagging with enzymes, removing collagen, or the ribosome’s function in translation, and do not pertain to purifying genomic DNA.