Joshua Lederberg is a Nobel Prize-winning American geneticist whose pioneering work on genetic recombination in bacteria helped propel the field of molecular genetics into the forefront of biological and medical research. In 1946, Lederberg, working with Edward Lawrie Tatum, showed that bacteria may reproduce sexually, disproving the widely held theory that bacteria were asexual. The two scientists' discovery also substantiated that bacteria possess genetic systems comparable to those of higher organisms, thus providing a new repertoire for scientists to study the genetic basis of life.

Continuing with his work in bacteria, Lederberg also discovered the phenomena of genetic conjugation and transduction--or the transfer of either the entire complement of chromosomes or chromosome fragments, respectively--from cell to cell. In his work on conjugation and transduction, Lederberg became the first scientist to manipulate genetic material, which had far-reaching implications for subsequent efforts in genetic engineering and gene therapy. In addition to...