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The Double Helix
Francis H. Crick and James D. Watson described the double helix structure of DNA. They got the Nobel Prize for their work in 1962. -
46 Human Chromosomes
Joe Hin Tjio defines 46 as the exact number of chromosomes inhuman cells. -
DNA Copying Enzyme
Arthur Kornberg and colleagues isolated DNA polymerase, an enzyme that would later be used for DNA sequencing. -
Cause of Disease Traced to Alteration
Vernon Ingram discovers that a specific chemical alteration in a hemoglobin protein is the cause of sickle cell disease. -
Semiconservative Replication of DNA
Matthew Meselson and Franklin Stahl demonstrate that DNA replicates semiconservatively: each strand from the parent DNA molecule ends up paired with a new strand from the daughter generation. -
Chromosome Abnormalities Identified
Jerome Lejeune and his colleagues discover that Down Syndrome is caused by trisomy 21. There are three copies, rather than two, of chromosome 21, and this extra chromosomal material interferes with normal development. -
First Screen for Metabolic Defect in Newborns
Robert Guthrie develops a method to test newborns for the metabolic defect, phenylketonuria (PKU). -
mRNA Ferries Information
Sydney Brenner, François Jacob and Matthew Meselson discover that mRNA takes information from DNA in the nucleus to the protein-making machinery in the cytoplasm. -
Genetic Code Cracked
Marshall Nirenberg and others figure out the genetic code that allows nucleic acids with their 4 letter alphabet to determine the order of 20 kinds of amino acids in proteins. -
Completion of the Human Genome Sequencing
The finished human genome sequence will be at least 99.99% accurate.