History of Molecular Genetics

• Beadle and Tatum


  experimented with bread mold and discovered a relationship between enzymes and genes (each gene is responsible for something/one gene, one enzyme), specific spots of DNA coded for a specific enzyme
• Frederick Griffith


  experimented with mice and found out the transforming principle (The change in the DNA of an organism by picking up the DNA from the dead organism or environment is referred to as the transformation.), leading to the discovery of DNA as the carrier of genetic information, did technical stuff with mice and the mice either died or not depending on the type of virus/bacteria injected
• Hershey and Chase


  discovered that DNA carried genetic information, believed that proteins were the carriers before their experiment, but didn't use transforming factor
• Avery, MacLeod, McCarty


  found out transforming factor is DNA
• Erwin Chargaff


  noticed that the nitrogenous bases are all in one ratio, found out using paper chromatography (20% guanine means 20% cytosine, so 30% adenine and 30% thymine)
• Maurice Wilkins


  Used X-ray crystallography to study the molecular structure of DNA. Worked with Franklin (did not collaborate well) to create a picture of the DNA molecule which allowed Watson and Crick to deduce the double helix structure of two strands.
• Phoebus Levene


  found out that DNA was made up of equal amounts of nitrogenous bases
• Meselson and Stahl

  Determined that DNA replication is semiconservative using N15 and N14 mediums to replicate DNA
• Rosalind Franklin


  used X-ray crystallography to determine that DNA is a double helix
• Friedrich Miescher


  discovered nucleic acids
• Watson and Crick


  "discovered" double helix structure of DNA and received a Nobel Prize
• The discovery of the structure of DNA by James Watson and Francis Crick was published in Nature in April 1953.
• Alfred Hershey and Martha Chase conducted an experiment where they labeled either protein or DNA from bacteriophage T2 with radioactive sulfur or phosphorus respectively. They found that only the DNA entered the bacteria, not the proteins.
• James Watson and Francis Crick's model of DNA was based on Rosalind Franklin's x-ray diffraction data, which showed two intertwining helices with complementary base pairing.
• Oswald Avery, Colin MacLeod, and Maclyn McCarty demonstrated that DNA could transform bacteria into virulent forms through genetic transformation experiments.