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How was DNA determined to be the genetic (hereditary / information carrying) material of life?

Chapter 16 - Molecular Basis of Inheritance. How was DNA determined to be the genetic (hereditary / information carrying) material of life?. Chapter 16 - Molecular Basis of Inheritance.

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How was DNA determined to be the genetic (hereditary / information carrying) material of life?

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  1. Chapter 16 - Molecular Basis of Inheritance How was DNA determined to be the genetic (hereditary / information carrying) material of life?

  2. Chapter 16 - Molecular Basis of Inheritance Once Morgan showed that genes are located on chromosomes, the two chemical components of chromosomes, ________________________, became the candidates for the genetic (hereditary) material of life…the race was on. DNA and Protein

  3. AIM: How was DNA determined to be the genetic (hereditary) material of life? Streptococcus pneumonia Streptococcus pneumonia Year: 1928 Smooth strain is pathogenic (can cause infection) due to the presence of a capsule that protects the bacterium from the host’s immune system.

  4. AIM: How was DNA determined to be the genetic (hereditary) material of life? Streptococcus pneumonia Streptococcus pneumonia Year: 1928

  5. AIM: How was DNA determined to be the genetic (hereditary) material of life? Streptococcus pneumonia Streptococcus pneumonia Year: 1928

  6. AIM: How was DNA determined to be the genetic (hereditary) material of life? Streptococcus pneumonia Streptococcus pneumonia Year: 1928 The harmless rough strain and harmless dead smooth strain were mixed together and incubated before being injected into the mouse…

  7. AIM: How was DNA determined to be the genetic (hereditary) material of life? Streptococcus pneumonia Streptococcus pneumonia What the? Year: 1928

  8. AIM: How was DNA determined to be the genetic (hereditary) material of life? Conclusion: There is some “factor” that carries information that is released by the Smooth strain upon heating and transforms the Rough strain into the smooth strain. In 1928, researchers had no idea what was doing this, but this set the stage for what would be a 14 year search by three scientists (Avery, MacLeod and McCarty) to figure it out…

  9. AIM: How was DNA determined to be the genetic (hereditary) material of life? You now know that something is transforming the Rough strain that is present in the Smooth strain. What would you do next?

  10. AIM: How was DNA determined to be the genetic (hereditary) material of life? Avery, MacLeod and McCarty’s experiment: (heat kill) They took the Smooth strain and heat killed it just like Griffith. Year: 1944

  11. AIM: How was DNA determined to be the genetic (hereditary) material of life? Avery, MacLeod and McCarty’s experiment: (heat kill) They then separated out the four major classes of macromolecules from the mixture. What do you think they did next? Year: 1944

  12. AIM: How was DNA determined to be the genetic (hereditary) material of life? Avery, MacLeod and McCarty’s experiment: (heat kill) They mixed each class separately with the Rough Strain and injected it into mice… What do you hypothesize their results were? Year: 1944

  13. AIM: How was DNA determined to be the genetic (hereditary) material of life? Avery, MacLeod and McCarty’s experiment: (heat kill) The mice receiving the Rough strain mixed with nucleic acids from the smooth strain died, while the other mice were fine. CONCLUSION: The transforming or information carrying factor is DNA!! Year: 1944

  14. AIM: How was DNA determined to be the genetic (hereditary) material of life? Avery, MacLeod and McCarty’s experiment: Skepticism It is the nature of critical thinkers like scientists to be skeptical of everything…and this finding was no exception. Most scientists believed (a dangerous notion) that protein was a better candidate due to their great heterogeneity (diversity) in contrast to DNA, which was highly uniform in nature. Year: 1944

  15. AIM: How was DNA determined to be the genetic (hereditary) material of life? Fig. 10.1A Bacteriophage This bring us to 1952, to the VIROLOGY Laboratory of Alfred Hershey and Martha Chase.

  16. AIM: How was DNA determined to be the genetic (hereditary) material of life? Fig. 10.1A Bacteriophage In order to figure out the type of nucleic acid, Hershey and Chase (1952) performed an experiment using viruses that infect bacteria called bacteriophages shown above. They obviously didn’t know what they looked like, but they knew that they were made solely of protein and DNA, and that they were able take over a bacterial cell and transform it into a virus-producing factory… The question was, was the protein or the DNA carrying the information to transform the cells?

  17. AIM: How was DNA determined to be the genetic (hereditary) material of life? Fig. 10.1A Bacteriophage BEFORE getting into the experiment, let’s compare the structure of a phage to an animal virus and then look at how phages work (how they infect bacterial cells)…

  18. AIM: How was DNA determined to be the genetic (hereditary) material of life? II. Bacterial virus (right; a bacteriophage) I. Animals virus (influenza – virus that causes the flu) Capsid – composed of protein, encloses nucleic acid (there are DNA as well as RNA viruses) All parts made of protein except DNA of course. Tail fibres – bind to surface of bacterium acting as ligands Envelope – similar to a plasma membrane – composed of phospholipids and integral membrane proteins that will act as ligands and bind to cell receptors to gain access to the cell. See video and figures Viruses are nothing more than packaged nucleic acid. Know the anatomy (structure) of these viruses…be able to draw and label them.

  19. AIM: How was DNA determined to be the genetic (hereditary) material of life? Reproductive cycle of a bacteriophage

  20. AIM: How was DNA determined to be the genetic (hereditary) material of life? Bacteriophage life cycle

  21. AIM: How was DNA determined to be the genetic (hereditary) material of life? Let’s now get back to the Hershey-Chase Experiment Is it the protein or the DNA that is the information molecule responsible for entering the bacterium and transforming it into a virus producing factory? Year: 1952

  22. AIM: How was DNA determined to be the genetic (hereditary) material of life? The experiment was performed using radioactive isotopes to be able to follow the protein or DNA. Isotopes of what elements would you use for protein/DNA labeling?

  23. AIM: How was DNA determined to be the genetic (hereditary) material of life? Let’s follow the protein first: Phages were initially prepared for the experiment by growing them in the presence of radioactive sulfur (35S) making the ONLY proteins radioactive as protein have sulfur (the amino acids methionine and cysteine), while DNA does not.

  24. AIM: How was DNA determined to be the genetic (hereditary) material of life? Let’s follow the protein first: 1. INFECTION: The phage was mixed with bacteria as shown above to allow them to infect the prokaryote.…

  25. AIM: How was DNA determined to be the genetic (hereditary) material of life? 2. AGITATE: After the bacteria were infected, the cells were banged around (agitated) using a blender so that anything stuck to the surface from the phage would fall off. We are only interested in what goes inside to transform the cell…

  26. AIM: How was DNA determined to be the genetic (hereditary) material of life? 3. CENTRIFUGE: The mixture was then centrifuged, which will pellet the bacterial cells (more dense) on the bottom of the tube. What do you do next?

  27. AIM: How was DNA determined to be the genetic (hereditary) material of life? 4. RADIOACTIVITY ASSAY: Is the cell pellet radioactive or is the supernatant radioactive? (The supernatant is the liquid portion of a centrifuged sample) Result – the supernatant was radioactive, the protein did not go in the cell. Does that mean the DNA went in for certain? How do we test if the DNA went in the cell?

  28. AIM: How was DNA determined to be the genetic (hereditary) material of life? You do the same experiment except instead of making the protein radioactive, you make the DNA radioactive in the beginning by growing the virus in radioactive phosphorus (32P)… Why 32P? Because protein does not have P.

  29. AIM: How was DNA determined to be the genetic (hereditary) material of life?

  30. AIM: How was DNA determined to be the genetic (hereditary) material of life?

  31. AIM: How was DNA determined to be the genetic (hereditary) material of life?

  32. AIM: How was DNA determined to be the genetic (hereditary) material of life? Conclusion DNA carries the information to transform the cell. DNA is the hereditary/information carrying material of life.

  33. Chapter 16 - Molecular Basis of Inheritance Timeline Recap: 1866 - Mendel’s work published never gaining popularity. 1875 - Mitosis figured out 1890 - Meiosis figured out 1900 – Mendel’s work rediscovered 1902 – Chromosomal Theory of Inheritance gains popularity 1910 – Morgan and co-workers show genes are on chromosomes – are genes protein or DNA?. 1928 – Griffith shows transformation – substance in S strain transferred to R, turning R into S 1944 – Avery, Macleod, and McCarty show this substance to be DNA 1952 – Hershey and Chase confirm concluding DNA to be the hereditary material of life. Very little was known about DNA at this point. How does this molecule work? How does it store hereditary information? The findings of Hershey and Chase catalyzed one of the most controversial stories in science… The race for the structure of DNA.

  34. Chapter 16 - Molecular Basis of Inheritance Movie: The secret of Photo 51 The race for the structure of DNA.

  35. Chapter 16 - Molecular Basis of Inheritance The road to the structure of DNA (but first a quick review of the structure)

  36. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA? A nucleotide

  37. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA?

  38. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA? Pyrimidines vs Purines

  39. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA?

  40. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA? Nomenclature

  41. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA? Draw a nucleotide found in RNA that contains a pyrimidine base and identify the base possibilities.

  42. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA? Draw a nucleotide found in DNA that contains a purine base and identify the base possibilities.

  43. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA? Draw CMP. Is CMP found in DNA or RNA?

  44. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA? DNA vs RNA

  45. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA? ? What do we do with monomers

  46. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA? Be able to draw and number the carbons

  47. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA?

  48. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA?

  49. Chapter 3 - The Molecules of Cells AIM: Describe the structure of DNA and RNA? The phosphate of one binds to the #3 C of the next. Will this be DNA or RNA? Explain.

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