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Miescher
In 1869 Meishcer observed cells found in great quantities in the pus from infections. Miescher collected bandages and washed off the pus. He experimented and isolated a new molecule, nuclein, from the cell nucleus. He determined that it was made up of hydrogen, oxygen, nitrogen and phosphorus . He was able to isolate nuclein now known as deoxyribose nucleic acid. Friedrich taught us that DNA came from the nuclein. -
Chargaff 2
Chargaff taught us how complimentary base pairs make a chromosome what it is. And the rules that go along with it. -
Chargaff
Chargaff began his research into DNA in 1944 and by 1950 he had experimentally determined crucial facts that led directly to the correct elucidation of its molecular structure. In particular, he demonstrated three rules which state that in DNA adenine-thymine base pair. Guanine-cytosine base pair.The number of adenine always equals the number of thymine .The number of guanine always equals the number of cytosine The number of purine always equals the number of pyrimidines -
Franklin
Around 1951 Franklin used an X-ray crystallography to get two sets of high-resolution photos of crystallized DNA fibers. She then used the two photos of the different fibers of DNA, one more highly hydrated than the other. From this she deduced the basic dimensions of DNA strands, and that the phosphates were on the outside of what was probably a helical structure. This was our first real look at DNA so we learned the basic structure of it. -
Hershey & Chase
In 1952 A.D. Hershey and Martha Chases provided further proof of Avery's demonstration that genes were DNA. They worked with a DNA virus called T2 that is a bacteriophage. Once the bacteriophage genes entered the cell the genes were transcribed and translated by the hosts RNA proving genes are DNA -
Watson & Crick
Watson and Crick discovered the three-dimensional model of physiological DNA (the double helix model) in 1953 using x-ray difaction data gathered by Maurice Wilkins. This discovery added to our prior knowledge by showing us that The DNA molecules consist of two polynucleotide strands that spirally twisted around each other and are coiled around a common axis to form a double-helix ,and the two strands are antiparallel -
Meselson and Stahl
In 1958 they showed that new DNA is made from copying the old. New DNA has to be made when cells divide. Each cell must recieve a full copy of the parent cell's DNA. During replication DNA strands separate, each strand acts as a template for synthesizing a new complementary strand. Each daughter cell has an old strand from the parent and a new strand. They found this by making clever use of notrogen isotopes and density gradient and centrifugation. Credited for proving the DNA replication model
