why nucleus is said to be acid

[mageshkov]

i do have doubt why nucleus is said to be acidic

[MisterATP]

It is because of DNA (hence it is acid!)

[MikeS]

Good question, I was once puzzled by it too. I always thought DNA contained nitrogenous bases, which are obviously basic. But why are they acidic?

I think the reason is in the phosphate groups. The ATGCs are basic, the (deoxy)ribose are sugers, hence neutral. But the phosphate groups are acidic. This is why when you store DNA, you store them as their salt form, which can be considered the conjugate base of DNA.

A detailed, graphical explanation is available here