Question

Why is ribonuclease often included in lysis buffer when extracting dna? What is its function?

Answer 1

This is an enzyme which will break down RNA, which helps to produce a lysate with DNA without RNA impurities.

Explanation:

Ribonuclease is an enzyme, the "ase" ending is a dead give-away that you are dealing with an enzyme.

The enzyme breaks down RNA (RNA = ribonucleic acid).

The goal of extraction is to purify the DNA as much as possible. Because the lysate (contents of a broken open cell) will have both DNA and RNA, the ribonuclease helps to remove the unwanted RNA.

Hope this helps!