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1869
Friedrich Miescher a swiss physician / biologist could isolate DNA using bandage collect with white blood cell he called that nuclein. -
1910
Phoebus Levene discovered nucleotides the components of DNA: adenine, guanine, thymine, cytosine, deoxyribose phosphate. He said that were four nucleotides in each cell but was false. -
1928
Frederick Griffith reported the first widely accepted demonstration of bacterial transformation he studied that 2 bacteria Streptococcus pneumoniae could transform to the other. He made a experiment with mouse but we could found the solution. They used R and mice lived, they took S and killed, he heat S and mice lives but then mixing S heated and R mouse die. -
1944
Avery MacLeod Maclyn they tried to explain what happened they took live R and heat-treated S and mixed with one of two enzymes: proteases: which destroys protein, DNase which destroys DNA. They discovered that mutation is made by DNA and not proteins. -
1951
Watson and Crick they described DNA as a double helix but these model was reality fast found to be incorrect. Linus Pauling and Robert Corey they proposed another model with 3 helix. -
1952 part 1
Erwin Chargaff an Austrian biochemist used paper chromatography and UV spectroscopy to examine the abundance of the nucleobases and he started to very something very odd. He made some experiments and found that Adenine and Thymine are very similar and Cytosine and Guanine are very similar also. He didn’t now the important of his discovering. Martha Chase American genetics and Alfred Hershey American genetics bacteriostatic they did an experiment using bacteriophage. -
1952 part 2
The bacteriophage is a virus that attacks bacteria is made of proteins and inside have ADN. They marked one bacteria with a radioactive sulfur in the outside part of the cell and they marked another bacteria with radioactive in the DNA zone and they released in the bacteria and then they centrifugation to separate. Experiment I: the virus was only marked in the part of the proteins and it released the DNA and then extracted when they centrifugation it was not marked. -
1952 part 3
Experiment II: the virus was released with the DNA marked so the virus was infected when they centrifugate. With that they found that the genetic material was in the DNA and not in the proteins. Franklin was the first to make a photo of the DNA but that was wet, but his boss take the photo from his desk and he decided to send the photo to Watson and Crick living in Cambridge. -
1953
In that year was discovered the exact photo of the DNA Watson, Crick and Wilkins they build a structure on april 25 because that these day is the DNA day.