Download WHO AM I

The Short History of
DNA
(SNOWBALL FIGHT!!!)
Modified by D. Dailey
Hewitt-Trussville High School
• From 1866-1953
Searching for Genetic Material
• WHO AM I
(1868):
– discovered DNA
– Isolated something
new from the nuclei
of eukaryotic cells of
white blood cells
• Later called DNA!!!
Searching for Genetic Material
• WHO AM I (1928):
– Studied effects of
virulent (virus-causing)
bacteria vs. nonvirulent
bacteria injected into mice
– Used transformation:
• Inserted foreign DNA and
changed protein/ trait
– believed that the
transforming agent was
an inheritance molecule.
WHO AM I Experiment
• Used the Pneumococcus bacteria
– Include2 types:
• a virulent S strain with a Smooth coat
– kills mice
• a non-virulent R Rough strain
– does not kill mice.
• Heat destroys (kills) living cells!!!
• When heated Smooth (harmful) cells (DEAD)
are mixed with living Rough (benign) cells and
injected into mice, the mouse dies.
–
http://www.quia.com/files/quia/users/hlrbiology/Animations/08_DNA_and_Proteins/Griffith_Mouse_E
xperiment.swf
Discovering the Structure of
DNA
WHO AM I (1950)
•Discovered a 1:1 ratio of adenine to
thymine and guanine to cytosine in DNA
samples from a variety of organisms.
Discovering the structure of
DNA
WHO AM I (1952)
• Photographed DNA using xray crystallography
• Worked with another
scientists named WHO AM I
• Awarded the 1962 Nobel
Prize for Physiology or
Medicine with Watson and
Crick
Discovering the structure of
Photo 51
DNA
WHO AM I
(1952)
•Obtained sharp X-ray diffraction
photographs of DNA (Photo 51)
•Watson and Crick used her data 
revealed its helical shape
•Watson and Crick went on to
win Nobel Prize (1962) for their
DNA model
Searching for Genetic Material
WHO AM I (1952)
– Confirmed DNA was genetic material
– Used bacteriophages (viruses)
– HYPOTHESIZED DNA, not protein,
is the hereditary material
Searching for Genetic Material
WHO AM I Experiment
Discovering the structure of DNA
WHO AM I (1953)
•Discovered double helix structure
•Solved the three-dimensional structure
of the DNA molecule
http://www.hhmi.org/biointeractive/dna/animations.html