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Oswald Avery
He continued research that Frederick Griffith started on the S and R strains. He would kill certain parts of the strain to figure out which part was making the S strain deadly. He inactivated the proteins and found that the R strain was still harmful so he concluded that it wasn't the proteins. But when they inactivated the DNA in the S strain when combined with the R strain, the R strain stayed harmless. This showed that it was the DNA that controlled the characteristics of the organism. -
Erwin Chargraff
He found that all species have the four nitrogen bases but that the concentrations were different. But he also found that the concentration of adenine was about the same as thymine and the concentration of cytosine was about the same as guanine. These are Chargraff's Rules. -
Rosalind Franklin
She was a chemist and X-ray crystallographer. She took an X-ray of DNA called Photo 51. This picture was an important part of discovering the structure of DNA. She discovered two forms of DNA. A and B. She focused on A because it showed more X-ray spots. But the form B showed the helix shape better which she determined was held together by the bases. -
James Watson and Francis Crick
They based their research on Rosalind Franklin's X-ray. They were given credit for finding that DNA has a double helix structure. The double helix is made of two chains of nucleotides. Then with Chargraff's Rules it showed how the bonds between the complimentary bases hold the chains together. They also found that half of the DNA ladder is used in DNA replication and that RNA carries the message between the DNA and the protein. -
Bibliography
Brainard, Jean. "Chapter 7." CK 12 Biology. N.p.: n.p., 2012. N. pag. Web.
"Concept 17 A Gene Is Made of DNA." Oswald Theodore Avery. N.p., n.d. Web. 28 Jan. 2015.
"Erwin Chargaff." Famous Scientists. N.p., n.d. Web. 29 Jan. 2015.
"Francis Crick." Famous Scientists. N.p., n.d. Web. 30 Jan. 2015.
"Rosalind Franklin." Famous Scientists. N.p., n.d. Web. 28 Jan. 2015.
