DNA History & Structure

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  • 1. DNA
  • 2. DNA
    • Deoxyribonucleic Acid
    • Very large molecule that carries genetic information of an organism
  • 3. DNA History
  • 4. 1865
    • Gregor Mendel generalized a set of rules governing inheritance, using a pea plant.
    • Described “units of heredity,” which are called genes.
  • 5. 1869
    • Meischer isolated DNA for the 1 st time
  • 6. 1928
    • Fred Griffith discovered transformation.
    • Worked as a health service worker.
    • Injected virulent bacteria into mice, resulting in death.
  • 7. 1944
    • Avery, MacLeod, and McCarty isolated the “factor” as the compound DNA.
    • DNA is defined as the genetic material!!
  • 8. 1948
    • Erwin Chargaff discovered DNA of all species are mainly the same.
    • The main difference is the proteins made by each individual.
  • 9. 1950
    • McKlintock published proof of transposons, “jumping genes,” by using corn.
    • She won the Nobel Prize in 1983 for her work.
  • 10. 1952
    • Rosalind Franklin took x-ray pictures of DNA crystals.
    • She was able to determine the relative shape and size of DNA.
  • 11. 1953
    • James Watson and Francis Crick, working together at Cambridge, discovered the structure of DNA.
    • They did this based on the x-rays and studies of Franklin.
  • 12. 1958
    • Meselson and Stahl used a density centrifugation to demonstrate semi-conservative replication of DNA.
  • 13. 1990
    • The Human Genome Project
      • A 15-year project designed to map EVERY gene in the human body!!
  • 14. 1997
    • Dolly, the lamb, was the 1 st mammal to be cloned from an adult using modern techniques of cloning.
    • She was cloned at the Roslin Institute in Edinburgh.
  • 15. 1999
    • 1 st chromosome is sequenced
  • 16. 2000
    • Human genome “draft” is completed.
    • Leaders announced the completion of a “working draft” DNA sequence of the human genome.
    • The post-genomic era begins!!
  • 17. Structure of DNA DNA and RNA: Polymers of Nucleotides
  • 18. DNA and RNA
    • Both are nucleic acids.
    • Consist of polymers of nucleotides, which are made up of:
      • A nitrogenous base
      • Sugar (Ribose or Deoxyribose)
      • Phosphate group
      • A repeating pattern, called a sugar-phosphate backbone
  • 19. DNA and RNA (con’t)
    • Nitrogenous bases are arranged like appendages along the backbone.
    • Nucleotides differ only in the nitrogenous bases:
      • Thymine (T) and Cytosine (C) are single-ringed structures
      • Adenine (A) and Guanine (G) are double-ringed structures
      • RNA uses Uracil (U) in the place of Thymine
  • 20. The Double Helix
    • Scientists working on the DNA structure were:
      • Linus Pauling
      • Maurice Wilkins
      • Rosalind Franklin
      • James Watson
      • Francis Crick
  • 21. Helix (con’t)
    • Using x-rays, Watson and Crick were able to determine the diameter of the helix was uniform and that it was a double helix.
    • After trying to replicate the structure, they found:
      • A sugar-phosphate backbone on the outside, forces the nitrogenous bases to the interior.
      • The 4 bases pair specifically.
      • The chemical side groups are bound with hydrogen bonds.
      • A binds to T and G binds to C, keeping the helix uniform.