Yes, DNA is acidic.
Why is DNA Acidic?
DNA's acidity stems from the phosphate groups in its backbone. Each phosphate group contains hydrogen atoms that can readily dissociate, leaving behind a negative charge. This release of protons (H+) is the defining characteristic of an acid. As multiple phosphate groups are present along the DNA strand, the overall effect is a significant negative charge and acidic nature. This is why DNA is attracted to positively charged molecules.
Several sources confirm this:
- Multiple references state explicitly that DNA's acidity is due to its phosphate groups (see provided references).
- The very name "nucleic acid" reflects this chemical property. As explained in a Reddit thread (https://www.reddit.com/r/explainlikeimfive/comments/pxtdmx/eli5_why_is_it_called_nucleic_acid_when_one_of/), the easily-lost proton from the phosphate group contributes to the overall acidity.
- While DNA also contains basic components, the acidic nature of the phosphate groups dominates. (https://www.aatbio.com/resources/faq-frequently-asked-questions/What-is-the-pH-of-DNA)
In short, the abundance of phosphate groups along DNA's backbone makes it an acidic molecule.
