Although all known cellular life and some viruses contain DNA, biologists in the

early 1900's had difficulty identifying DNA as the genetic material because of its

apparent simplicity. Although it is a long polymer, it is only composed of four

subunits-A, T, C, and G. It wasn't until the 1940's that scientists came to the

conclusion that DNA was in fact the molecule that contained the genetic

material. In 2-3 sentences, describe how DNA molecules store genetic

information for cells.