Q.What is transformation? Who discovered it, and in which organism?

Conjugation is 'bacterial mating' — one-way DNA transfer through direct cell-to-cell contact — discovered by Lederberg and Tatum in E. coli.

Conjugation is one of the mechanisms of genetic recombination in bacteria (along with transformation and transduction) in which genetic material is transferred directly from a donor (F+ or Hfr) cell to a recipient (F-) cell through a temporary cytoplasmic connection formed by a sex pilus. The donor cell possesses a fertility (F) plasmid; a single strand of this plasmid (which may carry chromosomal genes in Hfr strains) is transferred across the pilus into the recipient, where it is replicated, potentially converting the recipient's genotype/phenotype.

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Transduction is virus-mediated (bacteriophage-mediated) transfer of bacterial DNA between bacteria; Zinder and Lederberg discovered it in Salmonella typhimurium in 1952.

Definition: Transduction is one of the three natural mechanisms of genetic recombination in bacteria (the others being transformation and conjugation). In transduction, a bacteriophage (a virus that infects bacteria) accidentally packages a fragment of the host bacterium's DNA along with, or instead of, its own genome during the lytic cycle. When this phage subsequently infects a new bacterial cell, it injects this bacterial DNA fragment into the new host, which may then be incorporated into the recipient's genome by recombination.

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