01 dna history-stacy

1,519 views

Published on

Published in: Technology
0 Comments
2 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
1,519
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
0
Comments
0
Likes
2
Embeds 0
No embeds

No notes for slide

01 dna history-stacy

  1. 1. The History of DNA Structure Discovery Sec 4.1
  2. 2. 1869 – Johann Miescher <ul><li>Studied the nuclei of white blood cells </li></ul><ul><ul><li>Isolated the material using HCl (aq) and digestive proteins </li></ul></ul><ul><li>Named the substance nuclein </li></ul><ul><li>Found the material was rich in nitrogen and phosphorus </li></ul>
  3. 3. 1919 – Pheobus Levene <ul><li>Discovered that DNA was made up of chains of nucleotides </li></ul>ACID RIBOSE NITROGEN RICH
  4. 4. 1920 – DNA vs RNA <ul><li>thought that 4 nucleotides were connected in the same repeated pattern </li></ul><ul><li>protein have 20 amino acids which could be combined in many combinations </li></ul>bases location sugar DNA RNA bases location deoxyribose (one less oxygen) ribose sugar DNA RNA bases mainly inside nucleus mainly outside nucleus location deoxyribose (one less oxygen) ribose sugar DNA RNA AGCT AGCU bases mainly inside nucleus mainly outside nucleus location deoxyribose (one less oxygen) ribose sugar DNA RNA
  5. 5. 1928 – Frederick Griffith <ul><li>studied two strains of pneumococcus bacteria </li></ul><ul><li>rough strain = nonvirulent </li></ul><ul><ul><li>injection into mouse did not result in death </li></ul></ul><ul><li>smooth strain = virulent </li></ul><ul><ul><li>injection caused mouse to die </li></ul></ul>
  6. 6. Griffith’s Experiment
  7. 7. Griffith’s Conclusions <ul><li>some “factor” from the dead, virulent smooth strain “transformed” the living, non-virulent rough strain </li></ul><ul><li>non-virulent rough strain picked up DNA to become virulent </li></ul>
  8. 8. 1930 – Joachim Hammerling Acetabularia – type of alga nucleus at bottom of stalk
  9. 9. Hammerling’s Experiment <ul><li>Hereditary information is stored in the nucleus. </li></ul>no regrowth
  10. 10. Nucleus controls phenotypic properties of algae
  11. 11. Avery continued Griffith’s work: <ul><li>Purified chemicals from the heat-killed virulent bacteria, including DNA </li></ul><ul><li>Transformed non-virulent bacteria with each chemical </li></ul><ul><li>Only DNA resulted in death of the mouse </li></ul><ul><li>Conclusion: transforming agent is DNA thus DNA carries information to change a living cell </li></ul>
  12. 12. 1944 – Avery , McCarty & MacLeod <ul><li>continued Griffith’s work with pneumococcus </li></ul>pneumococcus & DNAse pneumococcus & protease Result Condition Tested non-virulent bacteria remained non-virulent pneumococcus & DNAse non-virulent bacteria  virulent bacteria pneumococcus & protease Result Condition Tested
  13. 13. 1940s – Joshua Lederberg <ul><li>demonstrated bacterial conjugation </li></ul><ul><ul><li>bacteria can exchange DNA </li></ul></ul><ul><li>bacteria have no nucleus or chromosomes </li></ul>
  14. 14. 1940s – Edwin Chargaff <ul><li>for all organisms </li></ul><ul><li>A = T and G = C </li></ul><ul><li>Chargaff’s Rule </li></ul><ul><li>organisms with more Gs and Cs tend to be more complex </li></ul>
  15. 15. 1952 – Hershey & Chase <ul><li>conducted experiments to definitively show that DNA is the hereditary material </li></ul><ul><li>bacteriophage used to infect bacteria </li></ul><ul><ul><li>bacterial virus </li></ul></ul>
  16. 17. Hersey & Chase <ul><li>What they knew: </li></ul><ul><ul><li>Virus are composed of DNA and protein </li></ul></ul><ul><ul><li>Virus infection reprograms a host cell to produce more virus </li></ul></ul><ul><li>Question: which viral component is responsible for the reprogramming, DNA or protein? </li></ul>
  17. 18. Hersey & Chase <ul><li>Bacteriophage / phage: virus that infects bacteria </li></ul><ul><li>Radioactive sulfur which labels proteins </li></ul><ul><li>Radioactive phosphorus which labels DNA </li></ul>
  18. 19. Hersey & Chase <ul><li>Virus injects DNA into host cell during infection, protein stays outside </li></ul><ul><li>DNA provides information to reprogram host cells to make more virus </li></ul><ul><li>In virus, DNA is the hereditary material, not proteins </li></ul><ul><li>Video: Website </li></ul><ul><li>http://highered.mcgraw-hill.com/olc/dl/120076/bio21.swf </li></ul>
  19. 20. 1950s – Maurice Wilkins & Rosalind Franklin
  20. 21. X-ray Crystallography <ul><li>physics approach to examining biological molecules </li></ul>
  21. 22. Rosalind Franklin’s X-rays <ul><li>The photo indicated: </li></ul><ul><li>Backbone of alternating phosphate and sugars </li></ul><ul><li>Backbone is a helical structure </li></ul><ul><li>Double helix structure (molecule is a uniform helix) </li></ul><ul><li>Nitrogenous bases are in the middle of the molecule </li></ul><ul><li>Bases are at right angles to the backbone </li></ul>
  22. 23. Base Pairing <ul><li>knew that each base could pair with itself </li></ul>
  23. 24. 1953 – James Watson & Francis Crick <ul><li>inspired by alpha-helix model of proteins </li></ul><ul><li>discovered how A + T and G + C bonded together </li></ul><ul><li>width of purine + pyrimidine bonds fit perfectly between the sugar-phosphate backbone </li></ul><ul><li>the double helix model offered an easy method for replication </li></ul>
  24. 25. 1953 – Linus Pauling <ul><li>Proposed the alpha helix secondary structure in proteins </li></ul><ul><li>Triple helix DNA model: 3 strands intertwined </li></ul><ul><li>What was wrong: </li></ul><ul><ul><li>Phosphate groups were shown as neutral molecules </li></ul></ul><ul><ul><li>Phosphates organized in the core for the helix: negative charges on oxygen would repel </li></ul></ul><ul><ul><li>Bases facing outwards </li></ul></ul>
  25. 26. Watson & Crick <ul><li>Regular pattern typical of helical structure reminiscent of the alpha-helix in proteins </li></ul><ul><li>Determined rules of base pairing: </li></ul><ul><ul><li>Size and hydrogen bonding </li></ul></ul><ul><li>Anti-parallel nature of strands </li></ul><ul><li>Original article published in Journal Nature </li></ul>
  26. 27. Watson & Crick <ul><li>Regular pattern typical of helical structure reminiscent of the alpha-helix in proteins </li></ul><ul><li>Determined rules of base pairing: </li></ul><ul><ul><li>Size and hydrogen bonding </li></ul></ul><ul><li>Anti-parallel nature of strands </li></ul><ul><li>Original article published in Journal Nature </li></ul>
  27. 28. Deductive Process: discovery of the structure of DNA <ul><li>Animation: http://www.dnaftb.org/dnaftb/19/concept/index.html </li></ul><ul><li>Video: http:// www.youtube.com/watch?v =sf0YXnAFBs8 </li></ul><ul><li>Song: http:// www.youtube.com/watch?v =FUA6_Ucw3i4&feature=related </li></ul>

×