Isolating Genes.

In 1969 the first gene was isolated. Genes are the basis of heredity, carried by DNA. The genetic code had been broken, so science knew how DNA worked. But the process for isolating genes was elusive. Dr. Jonathan Beckwith of Harvard solved the problem using simple viruses that infected the intestinal bacterium E. coli. Two viruses were used, both of which tended to incorporate one of the host's genes after infecting it. Each virus could incorporate different host genes, but both these viruses took the "lac" gene, which lets the bacterium eat lactose, a milk sugar.

DNA Strands Separated, Rejoined.

Beckwith removed the protein shell from both viruses, and heated their DNA separately, causing its two strands to separate. He then mixed the two types of DNA and slowly cooled them. Usually, DNA being cooled this way will seek its complementary...