Question

(i) Predict the experimental results of the following protocols. Support your prediction with a hypothesis.

• Polysaccharide-digesting enzymes are used to digest the encapsulated polysaccharide coat of the heated S form of the bacteria. The treated bacteria are then placed with unencapsulated pneumonia cells, which are then injected into a mouse.

• Heated encapsulated bacteria are treated with DNAase, a DNA-digesting enzyme. The treated bacteria are then mixed with unencapsulated pneumonia cells, which are injected into a mouse.

• All proteins are extracted from the heated encapsulated bacteria. The treated bacteria are then mixed with unencapsulated pneumonia cells, which are injected into a mouse.

Answer 1

The result of the experience is that R- bacteria are normally innocuous for the mice and only the S-bacteria kill them.But if R bacteria are mixed with dead S- bacteria they can also kill.

Something in the dead S- cells transforms the R-cells in "killer bacteria"

Hypothesis

It could be DNA ,a protein or fragment of the broken polysaccharide or fragment of the broken polysaccharide capsule. We can make 3 experiments that allow you to test for the effect of each of those different molecules.

Prediction, If I remove proteins or digest the polysaccharide coat DNA could still transform R-cells,hence the mice will die. But when I destroy DNA with the DNAse ,the transforming agent is not present anymore, hence the mouse will survive.