Genetic material is DNA and not protein h how did Griffith proof this
Answers
Answered by
1
While working with Streptococcus pneumoniae (the bacterium that causes pneumonia), Frederick Griffith observed a miraculous transformation in this bacterium. When you grow this bacterium on a culture plate, some produce shiny colonies (denoted as ‘S’) and some produce rough colonies (denoted as ‘R’).
The S strain bacteria have a polysaccharide coat which gives rise to smooth, shiny colonies. The R strain lacks this coat and hence, it gives rough colonies. Also, the S strain is virulent and causes pneumonia; while the R strain is non-virulent. He performed the following experiment with these strains and saw different observations.
S strain → Inject into mice → Mice develop pneumonia and die.
R strain → Inject into mice → Mice live.
Heat-killed S strain → Inject into mice → Mice live. (Griffith found that heating kills the bacteria).
Heat-killed S strain + R strain → Inject into mice → Mice die.
Thus he observed that not only did the mice injected with the heat-killed S strain + R strain die, but Griffith also recovered live S strain bacteria from these dead mice.
And so he concluded that this was because the R strain had somehow been ‘transformed’ by the heat-killed S strain. This he argued was due to the transfer of a ‘transforming principle‘ from the S strain to the R strain, which made the R strain virulent. Although significant, his observations did not identify the biochemical nature of the transforming principle.
The S strain bacteria have a polysaccharide coat which gives rise to smooth, shiny colonies. The R strain lacks this coat and hence, it gives rough colonies. Also, the S strain is virulent and causes pneumonia; while the R strain is non-virulent. He performed the following experiment with these strains and saw different observations.
S strain → Inject into mice → Mice develop pneumonia and die.
R strain → Inject into mice → Mice live.
Heat-killed S strain → Inject into mice → Mice live. (Griffith found that heating kills the bacteria).
Heat-killed S strain + R strain → Inject into mice → Mice die.
Thus he observed that not only did the mice injected with the heat-killed S strain + R strain die, but Griffith also recovered live S strain bacteria from these dead mice.
And so he concluded that this was because the R strain had somehow been ‘transformed’ by the heat-killed S strain. This he argued was due to the transfer of a ‘transforming principle‘ from the S strain to the R strain, which made the R strain virulent. Although significant, his observations did not identify the biochemical nature of the transforming principle.
Similar questions