Geneticists
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Wurde aktualisiert: 10 Dez 2018
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Created byZachary Chapman
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Hershey and Chase
To determine whether DNA
or proteins are the genetic
material
Used bacteriophages
cultured in radioactively
marked sulfur and
phosphorus to infect cells,
then used centrifugation to
separate out the isotopes
in the cells
The cells contained marked
phosphate, but not sulfur,
meaning that DNA is the
genetic material
-Watson and Crick
To find the structure
DNA and how it works
Used Wilkins and
Franklin's image of
DNA in order to model
the structure
DNA has a double helix
structure made of two
chains in an anti-parallel
structure connected by
nucleotides that form
base pairs with each otherPerioden
Mendel
Investigating what happens
in the transmission of
hereditary traits
Cross-bred homozygous
green (dominant gene)
and yellow (recessive gene)
pea plants, then continued
breeding the offspring for
a total of 4 generations
Inheritance of traits is
determined by "units,"
which are now known as genes
An offspring inherits one
allele from each parentSutton, Boveri, and Morgan
To determine the basis for genetic inheritance
1902 - Boveri studied reproduction in sea
urchins, while Sutton was studying meiosis
in sea creatures, specifically the fact that
during meiosis, the number of chromosomes
in sex cells is halved
1915 - Morgan studied heredity in fruit flies
Chromosomes carry genes from one
generation to the other, and a specific set of
chromosomes is necessary for normal growthGriffith and Avery
To determine if DNA or proteins are responsible
for genetic coding
1928 - While attempting to work towards a
vaccine for pneumonia, Griffith tested if mice
would survive when he injected different strains
of the disease into them. The mice injected with
a mixture of heat-killed viral pneumonia and live
non-viral pneumonia unexpectedly died
1944 - Isolated the "transforming principle" from
Griffith's experiment and then chemically tested
it to rule out possibilities for what it could be
Chargaff
To determine whether DNA is
responsible for differences
between species
Used paper chromatography to
isolate DNA, and then analyzed
the nucleotides via
spectrophotometry
Ratios of A:T and G:C in DNA are
always both 1:1
Different species have different
ratios of A and T to G and CWilkins and Franklin
To determine the structure of DNA
Used X-Ray crystallography to
image DNA
Discovered the helical shape of
DNA and that DNA contains two
strands attached together by
nitrogenous bases
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