Genetics Timeline

  • Gregor Mendel

    Gregor Mendel
    First Gregor Mendel self pollinated pea plants to ensure they were true-breeding. (parental generation) Then he cross pollinated the parental generation. (F1 generation) F1 was allowed to self pollinate. (F2 generation) His contribution was the Laws of inheritance, which are the law of segregation and the law of independent assortment.
  • William Bateson and Reginald Punnett

    William Bateson and Reginald Punnett
    First he crossed two long and purple flowers. (PpLl x PpLl) Then he observed and compared the offspring with his predictions. (9:3:3:1) Bateson and Punnett's contribution was that they discovered linked genes.
  • Thomas Hunt Morgan

    Thomas Hunt Morgan
    First he crossed a female fly with a male fly. (GgLl x ggll) Next he recorded results of the 2,300 offspring for color, which is either black or gray, and body, which is either long or vestigal. Then he found the recombination frequency, which was 17%. HIs contribution was discovering crossing over and genetic Recombination.
  • Archibald Garrod

    Archibald Garrod
    Archibald Garrod's contribution was that he proposed the relationship between between genes and proteins. His idea came from his observations of inherited diseases. His hypothesis was that an inherited disease reflects a person's inability to make a particular enzyme. This was proved to be right decades later.
  • Frederick Griffith

    Frederick Griffith
    First he injected R bacteria into a mouse, which did not kill the mouse. After that he Injected S bacteria into the mouse, which killed the mouse. Then he heated the S bacteria before injecting it into the mouse. That did not kill the mouse. Finally he heated S and R bacteria, which killed the mouse. Frederick Griffith's contribution was that he discovered transformation.
  • George Beadle and Edward Tatum

    George Beadle and Edward Tatum
    George Beadle and Edward Tatum's experiment was that they studied strains of mold that were unable to grow on the usual simple growth medium. They proved that each of the strains of mold lacked a single enzyme in a metabolic pathway that made a molecule that the mold needed. The contribution that they made was a major breakthrough in demonstrating the relationship between genes and enzymes.
  • Erwin Chargaff

    Erwin Chargaff
    Erwin Chargaff's contribution was the pairing rules, which are that Adenine only bonds with Thymine and Cyctosine only bonds with Guanine. He discovered this by experimenting with polynucleotide chains using newly developed paper chromatography.
  • Alfred Hershey and Martha Chase

    Alfred Hershey and Martha Chase
    The experiment that they conducted was that they mixed radioactively labeled phages with bacteria, which would infrect the bacteria cells. Then it was put in a blender to separate the phages outside the bacteria from the cells. After that they centrifuged the mixture. Alfred Hershey and Martha Chase's contribution was that they determined that DNA was a genetic material.
  • Maurice Wilkins and Rosalind Franklin

    Maurice Wilkins and Rosalind Franklin
    Maurice Wilkins and Rosalind Franklin were studying at King's College in London. That was were Franklin took an x-ray crystallographic photograph of DNA. The photo showed the basic shape of the DNA helix. Their contribution was discovering the basic shape and the helix of DNA.
  • James Watson and Francis Crick

    James Watson and Francis Crick
    James Watson and Francis Crick studied at Cambridge University. It was their that they made their contribution by discovering that DNA was a double helix made of two polynucleotide strands and that the diameter was 2 nm and Nitrogen bases were .33 nm apart. They did this by using wire models of nuvleotides to constuct a double helix, that they saw in Rosalind Franklin's photograph.
  • Marshall Nirenberg

    Marshall Nirenberg
    First Nirenberg linked together identical RNA nucleotides that had Uracil as their base. Then he added that poly-U to a mixture of ribosomes and other ingredients that are necessary for polypeptide synthesis. The mixture made the poly-U a polypeptide that contained one kind of amino acid, which was Phenylalanine. Finally, the amino acids specified by all the condons were determined. Marshall Nirenberg's contribution was that he deciphered the first codon.