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Friedrich Miescher
He was the first to identify DNA as a distinct molecule. He experimented and isolated a new molecule - nuclein - from the cell nucleus. He determined that nuclein was made up of hydrogen, oxygen, nitrogen and phosphorus and there was an unique ratio of phosphorus to nitrogen. He was able to isolate nuclein from other cells and later used salmon sperm. His works were later published in 1871. -
Hershey and Chase
They confirmed that DNA was genetic material. Hershey and Chase showed that when bacteriophages infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not. Hershey's and Chase's subsequent discoveries all served to prove that DNA is the hereditary material. -
Rosalind Franklin
Franklin and Gosling made a startling discovery. There were two forms of DNA shown in the X-ray images. Franklin was able to set up and improve the X-ray crystallography unit. Franklin was able to get two sets of high-resolution photos of crystallized DNA fibers. She used two 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. -
Chargaff
In DNA the number of guanine units equals the number of cytosine units, and the number of adenine units equals the number of thymine units. The relative amounts of guanine, cytosine, adenine and thymine bases varies from one species to another. This hinted that DNA rather than protein could be the genetic material. -
James Watson and Francis Crick
Watson and Crick built a model that explained the specific structure and properties of DNA after seeing Rosalind Franklin's X-ray pattern. Watson and Crick showed that each strand of the DNA molecule was a template for the other. Watson and Crick took a crucial conceptual step, suggesting the molecule was made of two chains of nucleotides. -
Meselson and Stahl
Meselson's and Stahl's contributions to DNA helped cement the concept of the double helix. the two had the experimental proof for the semi-conservative replication of DNA. They did this by inventing a new technique called density gradient centrifugation, which uses centrifugal force to separate molecules based on their densities. Their work was published in 1958. -
Bibliography 2
Davis, Tinsley H. "Meselson and Stahl: The Art of DNA Replication." Proceedings of the National Academy of Sciences of the United States of America. National Academy of Sciences, 28 Dec. 2004. Web. 22 Jan. 2017.
"Concept 20 A Half DNA Ladder Is a Template for Copying the Whole." Matthew Stanley Meselson :: DNA from the Beginning. DNA Learning Center, Cold Spring Harbor Laboratory, n.d. Web. 22 Jan. 2017
"Hershey–Chase Experiment." Wikipedia. Wikimedia Foundation, 18 Jan. 2017. Web. 22 Jan. 2017 -
Bibliography
"Erwin Chargaff." Wikipedia. Wikimedia Foundation, n.d. Web. 22 Jan. 2017.
"Concept 15 DNA and Proteins Are Key Molecules of the Cell Nucleus." Friedrich Miescher :: DNA from the Beginning. DNA Learning Center, Cold Spring Harbor Laboratory, 2002-2011. Web. 22 Jan. 2017.
"Concept 19 The DNA Molecule Is Shaped like a Twisted Ladder." Rosalind Franklin :: DNA from the Beginning. DNA Learning Center, Cold Spring Harbor Laboratory, 2002-2011. Web. 22 Jan. 2017.
