DNA

By Rsn7411222

  • Fredrick Griffith

    Fredrick Griffith
    1928
    He reported Griffith's Experiment which is a demonstartion of bacterial transformation.(in both form and function). He stated that changes are due to unidentified transforming principle or factor.
    This was later discovered as DNA on further studies by Oswald Avery.
    His experiment involved Pneumococci with two different forms -rough (R) and smooth (S).R considering avirulent when introduced with heat killed S the R transformed into S and mice were infected with pneumonia and death.

  • Oswald Avery

    Oswald Avery
    1944
    He worked with MacLeod and McCarty and showed Fred Griffiths "transforming principle" was DNA.
    They discovered that the nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next.
    His experiment involved removing of various organic compunds from bacteria, and to check if the remaining organic compound still be able to cause bacteria to transaform. He repeated this till he isolated DNA and found that no further transaformation occured with DN

  • Erwin Chargaff

    Erwin Chargaff
    He discovred two rules that helped lead to the discovery of DNA structure. His rules are known as Chargraff's rules.
    First Rule-The number of guanine units equals to number of cytosine units and the number of adenine units equals the number of thymine units.
    Second Rule- Composition of DNA is different in different species depending on amounts of A, G, T, and C bases making DNA the carrier of genetic information.
    His studies later helped Watson and Crick to develop DNA double helix model in futu

  • Rosalind Franklin

    Rosalind Franklin
    Her work contributed towards the studying of fine molecular structures- DNA, RNA, Viruses...She took X-ray pictures of DNA by using deffraction techniques.
    Her work on the X-ray diffraction of DNA is the key for Watson and Crick in developing double helix model of DNA. Her findings and data was shared with Watson without her knowledge which helped them to get ahead in the race.
    Her photograph 51 formed the base for Watson and Cricks DNA modeling.

  • Alfred Hershey and Martha Chase

    Alfred Hershey and Martha Chase
    They worked in studying viruses, nonliving particles smaller than a cell that can infect living things. Their experiments helped to confirm that DNA is the genetic material.
    One kind of virus that infects bacteria is known as a bacteriophage, which means bacteria eater, bacteriophage is made up of a DNA or RNA core and a protein coat.
    Hershey and Chase reasoned that if they could determine which part of the virus (Protein Coat or the DNA core) entered the infected cell, they would learn whether

  • Francis Crick and James D. Watson

    Francis Crick and James D. Watson
    Published an article --"Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid"
    After lot of trials and effort they finally developed the double helix model of the structure of DNA based on the clues from Franklin's x-ray evidence.
    They later discovred that the forces which hold two starnds together are hydrogen bonds which can form only between certain base pairs--A-T and G-C--forming a base pairing backing up Chargaff's rules.