GENETICS AND MOLECULAR BIOLOGY HISTORY OF DNA GENETICS AND MOLECULAR BIOLOGY

Friedrich Miescher 1869 Germany Isolated DNA From pus and fish sperm White, sugary Acidic with phosphorus Called it “nuclein”

Meanwhile . . . In Austria and England 1865 Gregor Mendel reported his pea findings Work ignored until 1900 1859 Charles Darwin published On the Origin of Species

William Sutton & Thomas Morgan at Columbia University 1902 Sutton observes chromosomes during meiosis Observations support Mendel 1909 Thomas Morgan worked with fruit flies Nobel prize: “factors” or genes on chromosomes

P.A. Levene 1920’s Rockefeller Institute Determined chemical makeup of DNA 5-carbon sugar phosphate group 4 nitrogenous bases Nucleotide Tetranucleotide theory* *It was wrong

Proteins or Nucelic Acids? Which was the Genetic Material? Both in nucleus Both in chromosomes Needed to be able to carry LOTS of info Needed to be able to replicate Nucleic acids had only 4 “letters” Proteins had 20 “letters”

Griffith 1928 England streptococcus pneunomia

Griffith 1928 England streptococcus pneunomia

Griffith 1928 England streptococcus pneunomia

Griffith 1928 England streptococcus pneunomia

Avirulent strain was transformed, but how and by what?

O.T. Avery 1943 Rockfeller Institute Transforming factor DNA (not protein) Nucleic acid is genetic material!

Edwin Chargaff Columbia University 1950 Amount of A = T; amount of G = C Amount of A + G = T + C Rejected Levene’s tetranucleotide theory

Linus Pauling California Institute of Technology 1948 Used models to discover alpha helix in proteins due to hydrogen bonds. Suggested DNA was helix

Hershey & Chase 1952 Blender Experiment Virus/Phage labeled with radioactive sulfur (S-35) or radioactive Phosphorus (P-32)

Hershey & Chase 1952 Blender Experiment Blender separates viral coat and bacterial cells

Hershey & Chase 1952 Blender Experiment

X-ray Crystallography DNA is crystallized Then x-rayed Produces an image Image is analyzed.

X-ray Crystallography King’s College, London Wilkins made crystal Franklin made image Franklin analyzed image Wilkins secretly shared analysis with Watson & Crick

Race for the Double Helix James Watson & Francis Crick Constructed a model 1953 Cavendish Lab Relied on Pauling, Franklin, Levene, Chargaff . . .

1953 Watson and Crick proposed: double helix complementary nucleotides P & Sugar backbones antiparallel strands semi-conservative replication templates Nobel prize with Wilkins in 1963

Other developments 1940: viral coat is protein, nucleic acid inside 1941: One gene : one polypeptide 1952: viral genetic material is nucleic acid 1957: Semi-conservative replication 1960’s: Genetic code 1960’s: Gene regulation 1973: DNA sequencing 1970’s: Gel Electrophoresis of DNA 1983: PCR 1990: gene therapy 1997: first GMO 2003: Human Genome Project

Some Observations Parallel pathways The odd traveler Teams Cross fertilization Specific skills, models, designs Simple organisms

Works Cited www.uni-tuebingen.de www.dnalc.org www.pbs.org www. nobelprize.org www. genetics.org www.biology-books.com www.access.mmhs.ca www.thunder.biosci.umbc.edu www.macroevolution.net www.onlinelibrary.wiley.com www.pauling.library.oregonstate.edu www.biochem.arizona.edu www.makingthemodernworld.org.uk www. chemistry.about.com www. paulingblog.wordpress.com