History of DNA

  • Gregor Mendel- Expirament

    Gregor Mendel- Expirament
    Gregor Mendels experiment started with pea plants. He took pea plants and self-fertilized them to get a speecific trait. The trait most famous in his expirament was flower color. He then crossed the purple flower with a white flower. When that generation matured he discovered that all of the flowers were purple. He then self polinated the purple flowers and got an approximate 3:1 ratio. Three being purple and one being white.
  • Gregor Mendel- Contribution

    Gregor Mendel- Contribution
    Gregor Mendels contribution to the discovery of DNA was major. He discovered the laws of segregation. This is that pairs of genes seperate during the production of gametes. The fusion of gametes brings back the pairs. He also discovered that some traits are dominant and some are recessive, and paired traits are either homozygous or heterozygous. He also created the first genotipic and phenotypic ratio.
  • William Bateson and Reginald Punnett- Experiment

    William Bateson and Reginald Punnett- Experiment
    In William Bateson and Reginald Punnet's expirament, they worked with sweet pea plants. The traits in these plants that they were expiramenting with was the flower color and pollen shape. They crossed two heterozygous purple flower and long pollen shape. When they observed there data they did not get the expected 9:3:3:1 ratio.
  • William Bateson and Reginald Punnett- Contribution

    William Bateson and Reginald Punnett- Contribution
    William and Reginald discovered that some genes are linked together, and are inherited together. They discovered that not all traits follow mendelian principles.
  • Thomas Hunt Morgan

    Thomas Hunt Morgan
    Hunt crossed fruit flies in his expirament. He crossed a heterozygous gray color, long wing with a homozygouse black color, vestigial wing. His results displayed 965 gray, long and 944 black, vestigial. He also got 206 gray, vestigial, and 185 black, long. His discovery was recombination frequency. He concluded that this is due to the crossing over of chromosomes. This gives you parental and recomvinant offspring.
  • Archibald Garrod.

    Archibald Garrod.
    His hypothesis for his expirament was that genes dictate phenotypes through enzymes, and iherited disease is the inhability to produce a specific enzyme. His contribution was that a lack of a certain enzyme can cause a certain inherited disease. An example of one of these diseases is albinism.
  • Frederick Griffith

    Frederick Griffith
    Griffith took bacteria causing pneumonia that was lethal and heated it. He mixed the heated lethal pneumonia and mixed it witha harmless pneumonia causing bacteria. The mixture was injected into mice and they were killed. From this data, he concluded that DNA could transform the bacteria to become lethal, and it could do the same thing with other cells.
  • George Beadle and Edward Tatum

    George Beadle and Edward Tatum
    Beadle and Tatum studied a bread mold. This mold could not grow on bread in normal conditions and they concluded that this mutation was due to the lack of an enzyme. From this expirament, Beadle and Tatum finalized the one gene- one enzyme hypothesis that Garrod started to formulate.
  • Erwin Chargaff

    Erwin Chargaff
    Chargaff and his co-workers calculated the amount of adenine in DNA was equal to the amount of thymine. They also discoverd that the amount of cytosine is equal to the amount of guamine. They discovered and contributed that adenine always bonded with thymine and cytosine always bonded with guamine. So with every adenine there is a thymine, and with every cytosine there is a guamine.
  • Alfred Hershey and Martha Chase

    Alfred Hershey and Martha Chase
    These scientists put radioactive protien in a bacterum and blended it and found that the liquid was radioactive, not the cell parts. They then put the radioactive pelet in the DNA, blended it and discovered that the radiactive material was in the cell parts, not the liquid. They found that DNA is what caused the production of other phages in the cell, not the protiens.
  • Maurice Wilkins and Rosalind Franklin

    Maurice Wilkins and Rosalind Franklin
    Rosalind Franklin took pictures of a singal strand of DNA using x-ray crystallography. This picture clearly defined the shape and structure of DNA. This was the first detailed picture of DNA, and the discovered that DNA was somewhat of a helix shape.
  • James Watson and Francis Crick

    James Watson and Francis Crick
    These scientists studied Franklins picture of DNA and finalized the shape and size of DNA. They found that the diameter of DNA is 2nm and found that DNA is a double helix shape. They contributed the shape of DNA and this made it easier for scientists to study it.
  • Marshall Nirenberg

    Marshall Nirenberg
    In Nirenberg's expirament, he synthesised an artificial RNA molecule and linked it to an identical molecule. He added the poly-U (UUU) to the amino acide, phenylalanine. The contribution that he made was that he discovered that the poly-U specifies to the acid phenylalanine. This also contributed to the discovery that the A, U, C, or G are grouped in threes to create a specific amino acid.