1 / 15

Discovery of DNA

Discovery of DNA. Fredrick Griffith – 1928 Oswald Avery – 1944 Alfred Hershey & Martha Chase - 1952. Griffith. S – Strain virulent (contains capsule – causes the disease) R – Strain non-virulent (no capsule – does not cause disease. Griffith – Background Information.

cspence
Télécharger la présentation

Discovery of DNA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Discovery of DNA Fredrick Griffith – 1928 Oswald Avery – 1944 Alfred Hershey & Martha Chase - 1952

  2. Griffith • S – Strain virulent (contains capsule – causes the disease) • R – Strain non-virulent (no capsule – does not cause disease

  3. Griffith – Background Information • Studied Streptococcus pneumoniae • Attempted to make vaccine for pneumonia • 2 strains R cells (rough) S cells (smooth)

  4. Griffith – Experiment / Results • E 1: Inject mice w/ live R cells  mice LIVE • E 2: Inject mice w/ live S cells  mice DIE • E 3: Inject mice w/ heat killed S cells  mice  LIVE • E 4: Inject mice w/ heat killed S cells and live R cells  mice DIE • Heredity material from S cells transform R cells into S cells.

  5. Griffith Conclusion • Transformation – transfer of genetic material from 1 cell to another or 1 organism to another.

  6. Avery Background Information • Tested to see if the transforming agent in Griffith’s experiment was Protein, DNA, or RNA

  7. Avery’s Experiment • E 1 – used protease to destroy proteins in heat killed S cells • E 2 – used RNA ase to destroy RNA in heat killed S cells • E 3 – used DNA ase to destroy DNA in heat killed S cells Separately mixed 3 batches of heat killed S cells with live R cells and injected the mice

  8. Avery’s Results • Cells missing proteins and RNA were able to transform R cells into S cells and kill the mice • Cells missing DNA did NOT transform R cells into S cells and mice lived.

  9. Avery’s Conclusion • DNA is the transforming agent in BACTERIA. DNA is responsible for transformation in bacteria

  10. Hershey / Chase Background Info • Tested whether DNA or proteins were heredity material viruses transfer when viruses enter a bacterial cell • Bacteriophage (phage) – virus that infects bacterial cells.

  11. Hershey/Chase Experiment • Used radioactive isotopes to label proteins and DNA in “phage”. • Radio Sulfur to label proteins • Radio Phosphorus to label DNA • Allowed protein labeled and DNA labeled phages to infect E-coli (bacteria) and tested E-coli for the radioisotopes.

  12. Hershey/Chase Results • They found ALL viral DNA and little of the protein had entered E-coli cells

  13. Hershey/Chase Conclusion • That DNA is the heredity material in viruses.

More Related