why are dna and rna called nucleic acids?what is acidic in them

DNA and RNA molecule are called nucleic acids because they are located in the nucleus of the cell. They play an important role in heredity transmission of characteristics. Chemically they contain both basic and acidic molecules within them. The backbone of these nucleic acids is made up of phosphate group with sugars. The phosphate group has taken up an electron and makes the structure acidic in nature.