The role of plasmids in conjugation was first described by Lederberg and Tatum (46) in –
**Core Concept**
The process of conjugation, a mechanism of bacterial genetic exchange, involves the transfer of genetic material from a donor bacterium to a recipient bacterium through direct cell-to-cell contact. Plasmids, small, self-replicating circular DNA molecules, play a crucial role in this process as they carry the genes responsible for the transfer.
**Why the Correct Answer is Right**
Lederberg and Tatum's work laid the foundation for understanding the role of plasmids in bacterial conjugation. They demonstrated that conjugation occurs between two bacterial cells, one serving as the donor (F+) and the other as the recipient (F-), with the donor transferring its plasmid-encoded F pilus to the recipient. This F pilus, encoded by the F plasmid, is essential for the formation of the conjugation bridge, facilitating the transfer of genetic material.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Lederberg and Tatum's work specifically focused on the role of plasmids in bacterial conjugation, not the discovery of the first antibiotic.
**Option B:** This option is incorrect because while Luria and Delbrück made significant contributions to the field of bacterial genetics, they did not describe the role of plasmids in conjugation.
**Option C:** This option is incorrect because Avery, MacLeod, and McCarty's work on the transformation of pneumococci was a separate discovery that demonstrated the role of DNA in bacterial genetics.
**Clinical Pearl / High-Yield Fact**
The discovery of plasmids in conjugation marked a significant milestone in understanding bacterial genetic exchange, highlighting the importance of horizontal gene transfer in shaping bacterial populations.
**Correct Answer:** C. 1946