DNA SBI3U

WHAT MACROMOLECULE CARRIES GENETIC INFORMATION? Agenda for October 22 nd Intro DNA notes 2.Create DNA

TIMELINE OF IDENTIFYING GENETIC MATERIAL 1.Genetic Material Transforms Bacteria - Frederick Griffith, DNA is the hereditary material - Oswald Avery, Colin MacLeod, and Maclyn McCarty, The Genetic Material is DNA - Alfred D. Hershey and Martha Chase, Erwin Chargaff, 1940’s and early 50's 5.M.H.F. Wilkins and Rosalind Franklin, early 50’s 6.James Watson and Francis H.C. Crick, 1953

DISCOVERY OF DNA Griffith 2 strains of bacteria  Smooth (pneumonia)  Rough (no pneumonia) Conclusion  Disease was passed  One strain was transformed into the other

DISCOVERY OF DNA Avery Isolated macromolecules from killed S cells  DNA, protein, lipids Found that living R cells exposed to S strain DNA turned into S cells Conclusion  DNA released  R strain incorporated this DNA into its cells

DISCOVERY OF DNA Hershey and Chase Bacteriophages – virus that attacks bacteria Labeled DNA and protein  Radioactive isotopes  DNA – labeled phosphorous  Proteins – labeled sulfur Conclusion  Viruses must inject DNA into living cell  DNA provided info needed to produce new viruses

DNA - DEOXYRIBOSE NUCLEIC ACID Store and transmit genetic information Composed of smaller nucleotides DNA is an ideal genetic material  store information  able to replicate  undergo changes (mutate)

STRUCTURE OF DNA Nucleotides – 3 parts Deoxyribose sugar Phosphate group Nitrogenous base  A, T, C, G

NITROGENOUS BASES 4 Bases  Adenine (A), Thymine (T), Cytosine (C), Guanine (G) Purine – Double ring  A and G Pyrimidine – single ring  T and C

CHARGAFF’S RULE Found amount of guanine equals amount of cytosine  Amount of adenine nearly equals thyamine Chargaff’s rule:C=GA=T

DISCOVERING STRUCTURE OF DNA X – Ray Diffraction Maurice Wilkins and Rosalind Franklin Photo 51 Indicated DNA was a double helix