History of DNA

Nucleic acids

1869

Nucleic acids were discovered in 1869 by Friedrich Miescher. When Friedrich was doing his experiment and he notice that in the white blood cells there was a natural acid and named nucleins.

DNA Components

1910

Phoebus Levene was a biochemist and a doctor had discover diferents components of DNA such as: adenine, thymine, guanine... Also he had defined phosphate sugar base and he called nucleotides. Unfortunedlhy he was wrong when he proposed that the estructure was organized in tetras and that for each module there was four nucleotides. He dies before the importance of his work was really discovered.

FREDERICK GRIFFITH

1929

Frederick Griffith was borned in 1879 and dies in 1941. He work as a bacteorologist. Some of the studies he had done were about the epidemiology and pathology.
In january of 1928 reported the first widely accepted demonstrations of bacterial transformotion.

Griffith experiment

1929

In his experiment Griffith studies two epidemiology and pathology of 2 strains. After doing his experiments he detect a bacterial transformation but hi can't explain the reason.

Avery MacLeod and McCarry experiment

1944

Some years after the experiment of Frederick Griffith experiment Avery MacLeod and McCarry replys the experiment to take conclusions and the conclusion that they arrive to was that the responsible about the chages experimented in Griffith experiment due to the DNA not protein

Erwin Chargaff

1952

Erwin Chagraff was a chemist that due to the 2n world war emigrates to the United States where he helps to discover the structure of DNA

CHARGAFF'S rules

1952

The chargaff's rules consists principally of the proportions between the differents elements that forms the DNA such as that (A/T =1).

Experiment of counting nucleoacids

1952

At 1953 James Watson and Fracisc Crick write on a paper what he think that DNA will be. He described as a double helix with sugars and phosphates at the center and the nucleobases facing the outside

Rosalind Franklin

1952

Rosalin Franklin was a X-ray crystallographer. If we look in books what we will read is that Rosalind had take a magnific pictures about what she thinks the B form of DNA was. The most famous picture is called photo 51. Before publish her image she wants to finish all her calculations. It was between Rosalind take the Photo 51 and that she finished the calculations that Maurice Wilkins takes the photo from her desk. FInally who recibes the nobel price was Wilkind for the work of Rosalin.

Hershey - Chase experiment

1952

Some years after all the theorys about the structure of DNA as a double helix was given as bad because they had no chemical sense. After make some experiments they arrive to the conclusion that proteins we're not genetic material although DNA waws it.

DNA

1952

At that moment it was a race between all the scientist to determine the structure of DNA, the problem was that DNA exists in two forms:
- dry form
- wet form
Most of the cientist were looking for the first form almost because it was the easiest.

First model 1953

1953

The first model of 1953 consists principally in the image 51 and the studies behind that photo but all the meriths reciebed Watson and Crick who later will reciebe the Nobel price.

Triple Helix

1957

Linus Pauling and Robert corey proposed a triple helix mode. Again this model had phosphate and sugar inside and nucleobases outside. But this model was also incorrect.