In a series of experiments, Griffith infected mice with nonvirulent R-strain bacteria and highly virulent S-strain bacteria. Heat-killed S bacteria were nonvirulent. However, the nonvirulent heat-killed S bacteria and the nonvirulent R bacteria together produced a virulent mixture. What did this demonstrate?

Question

Question 17 options:

A)

The molecules present on the outside of bacteria determine whether it's virulent or nonvirulent.

B)

The S-strain bacteria had not been killed completely.

C)

A transforming principle in the S bacteria allowed the nonvirulent R strain to become virulent.

D)

The translation of proteins, carbohydrates, lipids, and DNA is important in determining bacterial virulence.
Question 18 (5 points)

Answer 1

The experiment described refers to the classic work of Frederick Griffith, which demonstrated the phenomenon of transformation. The key observation was that when nonvirulent R-strain bacteria were mixed with heat-killed S-strain bacteria, the R-strain bacteria were transformed into a virulent form.

The correct answer to the question about what this demonstrated is:

C) A transforming principle in the S bacteria allowed the nonvirulent R strain to become virulent.

This transformation indicated that some component from the S-strain bacteria (later identified as DNA) was taken up by the R-strain bacteria, rendering them virulent. The experiment laid the groundwork for the later discovery of DNA as the genetic material.