genetic material is nucleic acid

agldacheng

The idea that genetic material is nucleic acid had its roots in the discovery of transformation in 1928. The bacterium Pneumococcus kills mice by causing pneumonia. The virulence of the bacterium is determined by its capsular polysaccharide. This is a component of the surface that allows the bacterium to escape destruction by the host. Several types (I, II, III) of Pneumococcus have different capsular polysaccharides. They have a smooth (S) appearance.
Each of the smooth Pneumococcal types can give rise to variants that fail to produce the capsular polysaccharide. These bacteria have a rough (R) surface (consisting of the material that was beneath the capsular polysaccharide). They are avirulent. They do not kill the mice, because the absence of the polysaccharide allows the animal to destroy the bacteria.
When smooth bacteria are killed by heat treatment, they lose their ability to harm the animal. But inactive heat-killed S bacteria and the ineffectual variant R bacteria together have a quite different effect from either bacterium by itself.