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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*
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*It was wrong
Proteins or Nucelic Acids?
Which was the Genetic Material?
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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
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Rejected Levene’s tetranucleotide theory
Linus Pauling
California Institute of
Technology
1948
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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
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DNA is crystallized
Then x-rayed
Produces an image
Image is analyzed.
X-ray
Crystallography
X-ray Crystallography
King’s College, London
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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
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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
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Parallel pathways
The odd traveler
Teams
Cross fertilization
Specific skills, models, designs
Simple organisms
Works Cited
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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