Question

Stability, as one of the properties of genetic material, was very evident in one of the very early experiments in genetics. Name the scientist and describe his experiment. State the conclusion he arrived at.

Answer 1

1. The stability of genetic material was unequivocally shown in Frederick Griffith's 1928 experiment. Griffith conducted experiments using two strains of Streptococcus pneumoniae bacteria: a virulent smooth strain (S) characterised by a polysaccharide capsule and a non-virulent rough strain (R) lacking the capsule. He administered four distinct combinations to mice: live S strain, live R strain, heat-killed S strain, and a blend of heat-killed S strain with live R strain.
2. Mice injected with the live S strain perished, whereas those injected with the live R strain or heat-killed S strain survived. Mice died after being injected with a mixture of heat-killed S strain and live R strain. Live S strain bacteria were found in their bodies during post-mortem examination.
3. Griffith's experiment established DNA as the genetic material, demonstrating its ability to preserve genetic information over generations. Avery, MacLeod, and McCarty established DNA as the transformative principle and confirmed its significance in inheritance.