What is the inference extracted from Griffith's transformation experiments?
Answers
Answer:
The bacterium Diplococcus pneumoniae causes pneumonia in humans. Frederick Griffith observed two strains of this bacteria. One strain called the smooth types (S) has polysaccharide forming a large capsule around the cell. The colony of such cells has a glistening appearance. The other strain bacterial cells do not have the polysaccharide layer and the colony formed by these cells has an irregular appearance and is called the rough type (R). The S-strain is virulent while the R-strain is non-virulent.
In this experiments, Griffith injected mice in the lab with live R-type of bacteria. They did not suffer from the disease. When he injected 'S'-type of bacteria, the mice died from the disease. However, when heat-killed S-type of bacteria were injected into the mice, they did not suffer from pneumonia. Then he injected the mice with a mixture of living R-type (non-virulent) with heat killed S-type (virulent) bacterial the mice suffered from the disease and died. Griffith observed that in the blood of dead mice, both R and S type of bacteria were present. He thus concluded that heat-killed smooth type bacterial caused a transformation of the living rough type bacteria. This experiment suggested that DNA and not proteins are the genetic material.
Answer:
Explanation:
Conclusion: Based on the observation, Griffith concluded that R strain bacteria had been transformed by S strain bacteria. The R strain inherited some 'transforming principle' from the heat-killed S strain bacteria which made them virulent. And he assumed this transforming principle as genetic material.