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DNA and Protein Synthesis

DNA and Protein Synthesis. What is DNA?. Contains the genetic information for making all the proteins in the cell. In the Beginning…. The world of science debated on what the genetic material was Some thought it was protein Others believed it was DNA. Evidence for a Genetic “Factor”.

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DNA and Protein Synthesis

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  1. DNA and Protein Synthesis

  2. What is DNA? • Contains the genetic information for making all the proteins in the cell

  3. In the Beginning….. • The world of science debated on what the genetic material was • Some thought it was protein • Others believed it was DNA

  4. Evidence for a Genetic “Factor” • 1928 – Frederick Griffith’s“Transforming Factor” Experiment • Conclusion: “Something” from Heat-treated Strain 1 “transformed” Strain 2 to become deadly

  5. DNA is Proven to be that Genetic Factor • 1944 – Oswald Avery and colleagues focused on two of the genetic factor candidates: protein and DNA • Repeated Griffith’s experiment, but with a modification   Proteases Mouse dies   DNases Mouse lives Conclusion – DNA is the transforming, thus genetic material

  6. Avery Questioned In the Scientific Community

  7. Final Proof that DNA is the Genetic Material • 1952 – Hershey-Chase Experiment • Virus = DNA (inside) + protein (outside) Conclusion: DNA was the genetic material due to viruses passing on DNA for reproduction

  8. The DNA “Twist” • DNA is a double helix • Every 10 nucleotides there is a 360 degree rotation • The structure of DNA is accredited to James Watson, Francis Crick and Rosalind Franklin

  9. Frame of Reference Where is the DNA located in eukaryotes? Prokaryotes?

  10. The Structure of DNA • DNA = deoxyribonucleic acid • DNA is a polymer built up from monomers • Monomers are called nucleotides

  11. The Structure of DNA Continued • Phosphate Group – provides the “backbone” of DNA 5’ end (5 prime end) • Sugar – called a deoxyribose; also part of the DNA “backbone” 3’ end (3 prime end) • Backbone of DNA called the sugar-phosphate backbone

  12. Nitrogenous Bases of DNA • Nitrogenous bases of DNA • Two Types • Pyrimidines  Thymine (T) •  Cytosine (C) • Purines  Adenine (A) •  Guanine (G) • Purines are double ringed, pyrimidines are single ringed

  13. Pairing of Bases • In DNAG hydrogen bonds with C • T hydrogen bonds with A G C C A T G T A C G T A T C G G T A C A T G C A T A

  14. Chargaff’s Rule • 1950 – Erwin Chargaff discovered: • A approximately equals T • G approximately equals C • This is true for all species! • In humans • A = 30.9% and T = 29.4% • G = 19.9% and C = 19.8%

  15. Let’s Put the Structure Together • Notice the following: • 5’ and 3’ ends • A:T and G:C • Hydrogen bond numbers • Sugar-phosphate backbone • Two strands are antiparallel

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