Question

Transformation in bacteria was discovered by:

• A. F. Griffith
• B. Lederberg and Tatum
• C. Avery
• D. McCarty

Hint:

For questions about scientific discoveries, remember the timeline. Griffith's discovery of the {phenomenon} of transformation (1928) came before Avery, McCarty, and Macleod's identification of DNA as the {transforming principle} (1944).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The question asks to identify the scientist who discovered the process of transformation in bacteria. 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.
Step 2: Detailed Explanation:


F. Griffith (1928): Conducted experiments with two strains of {Streptococcus pneumoniae}, a virulent (S) strain and a non-virulent (R) strain. He observed that when heat-killed S-strain bacteria were mixed with live R-strain bacteria and injected into mice, the mice died. He isolated live S-strain bacteria from the dead mice. He concluded that some "transforming principle" from the heat-killed S-strain had been taken up by the live R-strain, transforming them into the virulent S-strain. This was the discovery of bacterial transformation.

Lederberg and Tatum (1946): Discovered bacterial conjugation, a process of genetic transfer between bacterial cells through direct contact or a bridge-like connection.

Avery, McCarty, and Macleod (1944): Expanded on Griffith's work to identify the "transforming principle." Through a series of experiments using enzymes to destroy different types of molecules (proteins, RNA, DNA), they proved that DNA was the genetic material responsible for transformation.

Therefore, while Avery and McCarty identified the molecule responsible for transformation, it was F. Griffith who first discovered the phenomenon itself.
Step 3: Final Answer:
Based on the historical context of these discoveries, Frederick Griffith is credited with the discovery of bacterial transformation.