Question

Frederick Griffith performed an experiment where mice were killed when injected with a mixture of heat-killed S-type Streptococcus (HKS) and live R-type Streptococcus (LRS) but not with HKS or LRS separately. Mice were killed because

• A. Lipids from HKS made LRS virulent.
• B. RNA from HKS transformed LRS and made it virulent.
• C. Proteins from HKS made LRS virulent.
• D. DNA from HKS transformed LRS and made it virulent.

Answer 1

The correct option is D DNA from HKS transformed LRS and made it virulent.

Frederick Griffith performed an experiment where mice were killed when injected with a mixture of heat-killed S-type Streptococcus (HKS) and live R-type Streptococcus (LRS) but not with HKS or LRS separately. Mice were killed because when both the strains were mixed, DNA from HKS transformed to LRS and made it virulent. When the bacteria was heat killed, the DNA survived the heating process and was transformed to LRS when mixed. The DNA of HKS contains genes for smooth protective polysaccharide capsule. When these genes were transferred to LRS, it protected itself from the mice's immune system and killed the mice.

Thus, the correct answer is option D.