18 The bacterium A is pathogenic the bacterium B is benign W

18. The bacterium A is pathogenic; the bacterium B is benign. Which component of the bacterium A may turn the bacterium B to a pathogenic bacterium?

A. RNA

B. DNA

C. Lipids

D. Proteins

Solution

Answer:

18. (B) DNA

Transformation is the genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material from its surroundings through the cell membrane.

For transformation to take place, the recipient bacteria must be competent, that is should be in a state to accept the foreign, naked DNA.

Transformation in bacteria was first demonstrated by Frederick Griffith in 1928. He discovered that Streptococcus pneumoniae can be made virulent through exposure to heat inactivated virulent strains. Later the transforming principle was found to be DNA.