Question

Experiments conducted in the 1920s by Griffith involving the bacterium Diplococcus pneumoniae demonstrated that a substance from one bacterial strain could genetically transform other bacterial strains. What was the name of the substance capable of such transformation?

a) DNA
b) RNA
c) Protein
d) Lipid

Answer 1

Frederick Griffith's experiments in the 1920s with Streptococcus pneumoniae revealed that DNA was the substance responsible for the transformation of nonpathogenic bacteria into pathogenic bacteria.

Step-by-step explanation:

The substance capable of genetically transforming other bacterial strains, demonstrated by experiments conducted in the 1920s by Frederick Griffith, is DNA.

In Griffith's studies, two strains of the bacterium Streptococcus pneumoniae were used: the nonpathogenic rough (R) strain and the pathogenic smooth (S) strain. When Griffith injected mice with a mixture of live R strain and heat-killed S strain, the mice died and he recovered only the live S strain, indicating a transformation had occurred. The breakthrough was understanding that something within the heat-killed S strain, later identified as DNA by Avery, MacLeod, and McCarty, was responsible for this change. This led to the conclusion that DNA was the transforming principle capable of altering physiology and morphology of bacteria.