Download The Genetic Timeline

The Genetic Timeline
1868
Friedrick Miescher
From Pus soaked rags Miescher was able
to isolate the nuclei from white blood cells.
In the nuclei he finds a chemical he calls
“Nuclein”
Function is unknown of this mystery
chemical, but it contains a lot of phosphate
1910
Phoebus Levine
Over time Meischer’s nuclein was found
to be a major part of chromosomes
Through hydrolysis Nuclein contained
•Unique sugar called deoxyribose
•Phosphate
•4 kinds of nitrogen bases
Nitrogen-containing
Deoxyribose
Phosphate
(sugar)
bases
Nuclein
Adenine (A)
Thymine (T)
Cytosine (C)
Hydrolysis
Guanine (G)
Levine figured that each nitrogen base was attach to a sugar
Each sugar was then attached to a phosphate group
S
P
This arrangement of molecules was called a nucleotide and
is specifically named for the nitrogenNbase it contains
1910
Phoebus Levine
Meischer’s nuclein a major part of
chromosomes
Levine also thought that
these nucleotides
1. Adenine
Through hydrolysis Nuclein contained
•Unique sugar called deoxyribose
•Phosphate
•4 kinds of nitrogen bases
2. Thymine
On account of the new sugar the
substance is called deoxyribonucleic acid
or DNA
All occur in equal amounts
3. Cytosine and
4. Guanine
1927
Frederick Griffith
Worked with Smooth (lethal) and Rough
(harmless) cells of pneumonia and mice.
Found that a transforming principal
exists that can alter traits in bacteria and
that has an effect that is later heritable.
The Transforming Principal is unknown
1931
Henry Dawson
Refined Griffith’s findings and showed that
there was a chemical inside the dead
smooth cells and that that acted as a
transforming principal.
It could alter a rough cells traits to make it
smooth cells.
As well these new smooth cells are able to
pass on this new trait to their next
generation
1944
Avery Oswald
First to show that DNA was the
Transforming principal that everybody
was looking for and not protein.
BUT
World was not convinced
X
1952
Hershey and Chase
Through work with bacteria and viruses
they prove without a doubt that DNA and
not protein carries the information that is
needed for reproduction and that genes
are made from DNA
1948 - 1952
Chargaff
Finds that Levine is wrong in that there are
not equal amounts of the nucleotides
But
•No matter the species the amount of
Adenine always = to the amount of
Thymine.
•Amount of Guanine is = to the amount of
Cytosine