1. GENETICS AND MOLECULAR BIOLOGY
HISTORY OF DNA
GENETICS AND MOLECULAR BIOLOGY

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

3. 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

4. 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

5. 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

6. 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”

7. Griffith 1928 England streptococcus pneunomia

8. Griffith 1928 England streptococcus pneunomia

9. Griffith 1928 England streptococcus pneunomia

10. Griffith 1928 England streptococcus pneunomia

11. Avirulent strain was transformed,
but how and by what?

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

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

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

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

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

17. Hershey & Chase 1952 Blender Experiment

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

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

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

21. 1953 Watson and Crick proposed:
double helix
complementary
nucleotides
P & Sugar backbones
antiparallel strands
semi-conservative
replication
templates
Nobel prize with
Wilkins in 1963

22. 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

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

24. Works Cited www.uni-tuebingen.de www.dnalc.org www.pbs.org
www. nobelprize.org
www. genetics.org
www. chemistry.about.com
www. paulingblog.wordpress.com