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A Short History of DNA Technology

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A Short History of DNA Technology Review of Gel Electrophoresis and DNA Fingerprinting Write questions and answers in your notes What section of the DNA molecule is ... – PowerPoint PPT presentation

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Title: A Short History of DNA Technology


1
A Short History of DNA Technology
2
The History Of DNA
3
Miescher
4
Miescher
  • 1869
  • removed substance from pus off of old
    bandages
  • had acid properties, came from nucleus
  • called it nucleic acid

5
Griffith
6
1865
1928 - Frederick Griffith
Rough colonies
Smooth colonies
Transformation of Streptococcus pneumoniae
Living S cells
Living R cells
Heat killed S cells
Heat killed S cells mixed with living R cells
Living S cells in blood sample from dead mouse
capsule
Bacterial Strain
Injection
Results
7
Griffith
  • smooth and rough bacteria
  • dead smooth could transform live rough
    cells
  • accidental discovery

8
Avery, MacLeod, McCarty
9
1865
1944 - Avery, MacLeod McCarty
Purified DNA as transforming factor
  • Work not well-received
  • Protein more complex better able to store
    information

Oswald Avery
Colin MacLeod
Maclyn McCarty
10
Avery, McLeod, McCarty
  • separated cellular molecules
  • tested each for transforming abilities
  • carbohydrates, lipids, proteins were ineffective
  • only nucleic acids transformed the cells

11
Hershey and Chase
12
1865
1952 - Hershey Chase
Viral DNA (not protein) programs cells
Bacteriophages
Martha Chase Alfred Hershey
13
1865
1952 - Hershey Chase
Radioactive protein (35S)
Centrifuge and measure radioactivity in pellet
and supernatant
T2 Phage
Bacterium
Radioactivity in supernatant, but not pellet
Radioactive phage infects bacterial cells
Blender separates protein coats from bacterial
surface
14
1865
1952 - Hershey Chase
Radioactive DNA (32P)
Radioactivity in pellet, but not supernatant
Therefore, it is the viral DNA, and not protein,
that programs cells to make copies of the virus.
15
Hershey and Chase
  • chose organism composed only of protein and
    nucleic acid
  • infected cells with viruses tagged with
    radioisotopes
  • tagged proteins were not transferred
  • tagged nucleic acids were transferred

16
Chargaff
17
1865
1947 - Erwin Chargoff
DNA bases follow certain rules
  • Base composition is species specific
  • A T, C G for all species

18
Chargaff
  • analyzed percentage of each base in DNA samples
  • found adenine thymine
  • found cytosine guanine

19
Wilkins and Franklin
20
1865
1953 - Franklin Wilkins
Elucidation of the helical nature of DNA
Rosalind Franklin
Photographic film
X-ray source
Crystallized DNA
Maurice Wilkins
21
Wilkins and Franklin
  • X-ray crystallography on DNA to establish shape,
    dimensions of molecule

22
Watson and Crick 1953
23
1953 - Watson Crick
1865
Description of the 3-D structure of DNA
Francis Crick James Watson
24
Watson and Crick
  • did no original research/ relied on work of
    others
  • analyzed X-ray crystallography, biochemistry
  • hypothesized double-stranded helix in 1953

25
1953 - Watson Crick
1865
  • What they deduced from
  • Franklins X-ray data
  • Double helix
  • Uniform width of 2 nm
  • Bases stacked 0.34 nm apart
  • Chargoffs rules
  • Adenine pairs with thymine
  • Cytosine pairs with guanine

26
1953 - Watson Crick
1865
  • What they came up with on their own
  • Bases face inward, phosphates and sugars outward
  • Hydrogen bonding
  • Hinted at semi-conservative model for
    replication

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  • Review of Gel Electrophoresis and DNA
    Fingerprinting
  • Write questions and answers in your notes
  • What section of the DNA molecule is used for DNA
    fingerprinting?
  • 2)How is the DNA polymer cut?
  • 3) What factors determine how fast a segment of
    DNA migrates in the gel?
  • 4) What is the purpose of the marker?
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