Penicillin was discovered accidentally by Sir Alexander Fleming in 1928 at St. Mary's hospital in London when he forgot to clean a Petri dish before leaving on vacation. Fleming's experimentation with the left-behind mold led him to discover its dissolving effects on the Staphylococcus aureus bacterium. Through further trials he discovered that a pure culture of the mold effectively killed the harmful bacteria.
The American chemist (of Polish origin) Frank. B Colton invented the oral contraceptive with his synthetic hormone pill (Enovid) introduced in 1957. The pill worked by preventing ovulation in the female and thus tricking the body into preventing conception. Oral contraceptives are still used today and are sources of controversy in arguments such as teen pregnancy.
Swiss physician Friedrich Miescher first isolated DNA in 1869, which he termed "Nuclein." In 1919, Phoebus Levene found Nuclein to consist of a string of nucleotide linked together by phosphate groups. It wasn't until 1953, however, that James Watson and Francis Crick discovered the first correct model of double-helix DNA structure. In 1957, Crick explained the relationship between DNA, RNA and proteins that would change the view of genetics forever.
Genetic engineering --- or cloning, known by most people ‚ was discovered by researchers Stanley Cohen and Herbert Boyer in 1973. Their discovery allowed genes to be transplanted between species, creating a plethora of medical products such as synthetic insulin, a clot dissolver and growth hormones.