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DNA: Deoxyribose Nucleic Acid The Genetic Material

DNA: Deoxyribose Nucleic Acid The Genetic Material. Chapter 2: Introduction to DNA. DNA. D eoxyribose n ucleic a cid  type of nucleic acid What is the other type of nucleic acid? RNA DNA function to hold genetic code Genetic code = genetic instructions to make proteins

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DNA: Deoxyribose Nucleic Acid The Genetic Material

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  1. DNA: Deoxyribose Nucleic AcidThe Genetic Material Chapter 2: Introduction to DNA

  2. DNA • Deoxyribose nucleic acid  type of nucleic acid • What is the other type of nucleic acid? • RNA • DNA function • to hold genetic code • Genetic code = genetic instructions to make proteins • DNA is found in nucleus of eukaryotic cells • Found in nucleoid region in prokaryotes

  3. The Short History of DNA and Genetics (Part 1) • From 1866-1953

  4. The secret of Life video • https://www.youtube.com/watch?v=JjO6n85wq8A

  5. Searching for Genetic Material • Gregor Mendel (1866): • discovered that inherited traits are determined by discrete units, or 'genes,’ - passed on from the parents. • Freidrich Miescher(1868): • discovered DNA • Isolated something new from the nuclei of eukaryotic cells • Later called DNA!!!

  6. Searching for Genetic Material • Thomas Hunt Morgan (1910): • Worked with fruit flies • Specifically eye color of these flies! • Discovered genes are located (linked) on chromosomes

  7. Searching for Genetic Material • Fredrick Griffith (1928): • Studied effects of virulent (virus-causing) bacteria vs. nonvirulent bacteria injected into mice • Used transformation: • Inserted foreign DNA and changed protein/ trait • believed that the transforming agent was an inheritance molecule.

  8. Non-virulent vs. Virulent Bacteria ROUGH: harmless SMOOTH: kill

  9. NOT HARMFUL/BENIGN BAD/HARMFUL

  10. Griffith's Transformation Experiment • Used the Pneumococcus bacteria • Include2 types: • a virulent S strain with a Smooth coat • kills mice • a non-virulent R Rough strain • does not kill mice. • Heat destroys (kills) living cells!!! • When heated Smooth (harmful) cells (DEAD) are mixed with living Rough (benign) cells and injected into mice, the mouse dies. • WHY?

  11. Searching for Genetic Material

  12. Searching for Genetic Material Oswald Avery, Colin MacLeod, & Maclyn McCarty (1944): • Reported that “transforming agent” in Griffith's experiment was DNA. • Also used the Pneumococcus bacteria and test tubes (NOT mice)

  13. The Avery, et al. Experiment http://wps.aw.com/bc_russell_igen_me_1/ • Used S (harmful) strain • Opened up the cells • Isolated • DNA, proteins and other materials SEPERATELY • Mixed R bacteria with these different materials • Only those mixed with DNA were transformed into S bacteria. OTHER S CELL PARTS (sugar/RNA) + R Bacteria  S PROTEINS + R Bacteria  S DNA + R Bacteria  TEST TUBES

  14. Discovering the Structure of DNA • Edwin Chargaff (1950) • Discovered a 1:1 ratio of adenine to thymine and guanine to cytosine in DNA samples from a variety of organisms.

  15. Chargaff's Rule (Data)

  16. Discovering the structure of DNA Chargaff’s Rules A = T C = G

  17. Discovering the structure of DNA Maurice Wilkins (1952) • Photographed DNA using x-ray crystallography • Worked with another scientists named Rosalind Franklin • Awarded the 1962 Nobel Prize for Physiology or Medicine with Watson and Crick

  18. Linus Pauling’s TRIPLE helix • Linus Pauling • (1954) • proposed a triple helix structure for DNA

  19. Discovering the structure of DNA Photo 51 Rosalind Franklin (1952) • Obtained sharp X-ray diffraction photographs of DNA (Photo 51) • Watson and Crick used her data  revealed its helical shape • Watson and Crick went on to win Nobel Prize (1962) for their DNA model

  20. How did PHOTO 51 reveal DNA’s helical shape?

  21. She finally gets credit  Rosalind Franklin University of Medicine and Science, located on Green Bay Road in North Chicago, Illinois

  22. Searching for Genetic Material Alfred Hershey & Martha Chase (1952) • Confirmed DNA was genetic material • Used bacteriophages (viruses) • HYPOTHESIZED DNA, not protein, is the hereditary material

  23. Searching for Genetic MaterialHershey and Chase Experiment

  24. Searching for Genetic Material Hershey and Chase Experiment Animation https://www.youtube.com/watch?v=g9JQURwseIY

  25. Discovering the structure of DNA • James Watson & Francis Crick (1953) • Discovered double helix structure • Solved the three-dimensional structure of the DNA molecule https://www.youtube.com/watch?v=VegLVn_1oCE

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