Question

“Transforming Principle” was given by:

• A. Maclyn McCarty
• B. Frederick Griffith
• C. Alfred Hershey
• D. Watson and Crick

Answer 1

The Correct Option is B

In the field of biology, the term "Transforming Principle" was introduced by Frederick Griffith, a bacteriologist whose experiments conducted in 1928 led to this discovery. He performed a series of experiments using two strains of Streptococcus pneumoniae bacteria. The key steps of his experiment included: 

• Smooth Strain (S): This strain had a polysaccharide capsule, making it virulent and able to cause disease.
• Rough Strain (R): This strain lacked a capsule and was non-virulent.
• Experimentation: Griffith found that when he injected mice with a mixture of heat-killed virulent S strain and live non-virulent R strain, the mice died. Moreover, live S strain bacteria could be isolated from the dead mice.

Griffith concluded that some "transforming principle" from the heat-killed S strain bacteria transformed the R strain into a virulent form. This groundbreaking concept later proved to be pivotal in identifying DNA as the genetic material.

Answer 2

The "Transforming Principle" was first identified by Frederick Griffith in 1928 during his experiment with Streptococcus pneumoniae bacteria. Griffith discovered that non-virulent (harmless) bacteria could be transformed into virulent (disease-causing) bacteria when exposed to heat-killed virulent bacteria. This transformation was later found to be caused by the transfer of genetic material, which was referred to as the "transforming principle."

• Maclyn McCarty, working later in 1944, identified that the transforming principle was DNA.
• Alfred Hershey and Martha Chase later confirmed that DNA was the genetic material in their famous experiment with bacteriophages.
• Watson and Crick are credited with discovering the structure of DNA, but they did not give the "transforming principle."