Question

♥♥Hey♥♥ PLEASE HELP ME Please don't Copy paste ⚠ Describe the experiments that established the identity of ‘transforming principles’ of Griffith. Class 12 CBSE

Answer 1

Transforming Principle

Griffith who was researching for the cure of pneumonia, experimented with Streptococcus pneumoniae and Mice observed the following :

• When the rat was injected with a S - strain bacteria, it ended up dying.

• On the contrary, the rat survived when injected with a R - Strain.

S - Bacteria :

• They have a smooth appearance.
• They are dangerous.
• They live a solitary existence

R - Bacteria :

• They have a rough appearance
• They are not virulent
• They form colonies

When the same bacteria were heated and then injected, the results were reversed.

• Earlier, the s strain bacteria was able to withstand the immune responses of the host because of polysaccharide protective layer. Heating of the strain would lead to degeneration of the capsule, thus leaving the strain vulnerable.

• On the other hand, the bacterial genome underwent transformation in the R - Strain, providing it with an ability to form the polysaccharide layer.

• Griffith found samples of S strain bacteria injected with Heated R Strain, arriving at the Transforming Principle.