Question

In 1928, Frederick Griffith's experiments with Streptococcus pneumoniae suggested that

A) bacteria do not incorporate the DNA of other bacteria.
B) attenuated R (rough) bacteria easily revert to the wild type (virulent).
C) RNA was the genetic material.
D) heat-killed bacteria could somehow "transform" live bacteria.
E) protein was the genetic material.

Answer 1

In 1928, Frederick Griffith's experiments with Streptococcus pneumoniae demonstrated the process of bacterial transformation, in which external DNA is taken up by a cell, changing its characteristics. Injection of a mixture of live R and heat-killed S strains caused the mice to die, suggesting some sort of transformation occurred.

Step-by-step explanation:

In 1928, British bacteriologist Frederick Griffith conducted experiments with two strains of Streptococcus pneumoniae - rough (R) and smooth (S) - to demonstrate bacterial transformation, a process in which external DNA is taken up by a cell, changing its morphology and physiology. He injected mice with the live R strain and they survived. When he injected mice with a mixture of live R strain and heat-killed S strain, the mice died. This led Griffith to conclude that the heat-killed S strain somehow transformed the live R strain, which suggested that external DNA could be incorporated into bacterial cells.