AP BIOLOGY

Detailed explanation-1: -As part of his experiments, Griffith tried injecting mice with heat-killed S bacteria (that is, S bacteria that had been heated to high temperatures, causing the cells to die).

Detailed explanation-2: -In Griffith’s experiment, the virulent S. pneumoniae that has a smooth (S) capsule in its appearance was capable of causing lethal infections upon injection into mice (Fig. 1.1).

Detailed explanation-3: -Pneumococcus bacteria include two strains, a virulent S strain with a Smooth glycoprotein coat that kills mice (left), and a non-virulent R Rough strain that does not (middle).

Detailed explanation-4: -What was Griffith able to conclude from his experiment? He was able to conclude that genes from the harmful bacteria transferred to the harmless bacteria, and transformed them.

Detailed explanation-5: -Experiment 4: Griffith mixed his heat-killed, disease-causing bacteria with live, harmless bacteria and injected the mixture into the mice. The mice developed pneumonia and died. Griffith concluded that the heat-killed bacteria passed their disease-causing ability to the harmless strain.