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Frederick Griffith (1928)

Frederick Griffith (1928). Frederick Griffith (1928). Frederick Griffith (1928). Frederick Griffith (1928). ?. ?. Frederick Griffith (1928). Avery, McCarty & MacLeod (1944). Only DNA (not protein, lipid or carbohydrates) “TRANSFORM” bacteria. Hershey & Chase (1952).

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Frederick Griffith (1928)

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  1. Frederick Griffith (1928)

  2. Frederick Griffith (1928)

  3. Frederick Griffith (1928)

  4. Frederick Griffith (1928) ? ?

  5. Frederick Griffith (1928)

  6. Avery, McCarty & MacLeod (1944) Only DNA (not protein, lipid or carbohydrates) “TRANSFORM” bacteria

  7. Hershey & Chase (1952) “Bacteria eaters”- Phage virus particles (image from the 1990s)

  8. Hershey & Chase (1952) Viruses are made of protein and nucleic acid ONLY “Something” in the virus enters the cell and gets incorporated into the genetic material (whatever that might be) of the bacteria That “something” transforms bacteria to turn them into virus production factories Protein is full of a lot of the atom Sulfur; nucleic acids have very little DNA is full of the atom phosphorus; proteins have very little

  9. Hershey & Chase (1952)

  10. Hershey & Chase (1952) PROTEIN coat DNA “Bacteria eaters”- Phage virus particles (image from the 1990s) Host Cell

  11. Generally accepted at the time: Nucleic acids are made of four components: Phosphate group: Sugar (deoxyribose & ribose): Nitrogenous bases: Pyrimidines (1-ring): Purines (2-ring):

  12. Erwin Chargaff (1947) All living cells have DNA (plus many that are not living) Between species there is wide variation in the overall percentages of A, T, G & C However, in all species A = T, C = G E.g.- Human A- 30.3%, T= 30.3 %, G= 19.5%, C= 19.9% “Chargaff’s Rules” Also, a cell before meiosis has twice as much DNA as a cell (sperm, egg) after

  13. Franklin (1951- 52) “X-ray diffraction crystallography”

  14. Franklin (1951- 52) Image #51: Helix Repeating units “unit cell” of specific parameters Phosphates: on outside= “backbone” C2 form Parallel width along length

  15. Watson & Crick (1952)“Goldilocks” Backbone (sugars and phosphates) parallel along length Bases (purines and pyrimidines) fill in the space between the “rungs” But how?

  16. Watson & Crick (1952) Many “Ah-Hahs” A bonds to T (2 bonds), C bonds to G (3 bonds) and NOT vice versa Consistent with whose previous research? Presented wrong in their original papers (gave both 2 bonds)

  17. “Nucleotides” Watson & Crick (1952) Other “Ah-Hahs” C2 form? All the data fit with Franklin’s, Chargaff’s, etc… conclusions

  18. Watson & Crick (1952) All the data fit with Franklin’s, Chargaff’s, etc… conclusions And it looks good too!

  19. Watson & Crick (1952) Part I- the model (what it looks like) Part II- how it works (the “secret of life”) “Complimentarity” & replication “The Central Dogma” & information storage

  20. Watson & Crick (1952) DNA RNA PROTEIN “Replication” “The Central Dogma” & information storage Enzymes Cell Structures Lipids Nucleic Acids Carbohydrates

  21. Watson & Crick (1952) “Complimentarity” & replication Their Model (paper #2) “Semi-conservative” replication:

  22. Meselson & Stahl (1958) “Classic” experiment testing Watson & Crick’s model.

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