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P. A. Levene
P. A. Levene discovered the basic structure neucleotides (subunits of nucleic acid), witch is a phosphate, 5-carbon sugar molecules and one of four nitrogenous basis. He found that the DNA neucleotide consisted of a phosphate, deoxyribose, and one of four ntrogeous basis; Guanine, cytosine, adenine, and thynine. He also found out that RNA neucleotide consisted of sugar ribose, a phosphate and a nitrogenous base. -
fredrick Grifith
Grifith was the first to discover the transformation of cells in his experiment in testing 2 strands of streptococcus pneumonane cells that cause pneumonia. He tested the relationship between the cells and how one caused pneumonia (S) and the other that did not (R). Then he made a test where he killed the (S) strand and put it together with the non infectious R strand and when when he did this the dead S strand transformed back into living through the live R strand. -
Oswald Avery
in addition to Griffith's discovery, Avery conucted experiments to find out what macromolecule makes the living R cell transform into a living S strand. He isolated macromolecules from the dead S strand and mixed the living R strand in with those isolated macromoecule. Oswald found out that traces of DNA from the dead S strand transformed the R strand to a living S, -
Linus Pauling
Linus Pauling discovered the Alpha Helix structure by drawing a polypeptide chain using the chemical and stereochemical constraints. which ment creating an almost exact replica. He finally concuded that the polypeptide strain was a single layer helix(Alpha helix).
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Erwin Chargaff
He discovered that in nitrogenous basis, gaunine equals the amount of cytosine and that adenine equals the amount of thynine. -
maurice Wilkins
While working in kings college along with Franklin. They were expirementing with X-ray difraction, which is the X-raying of DNA. So he contributed to the discovery of the double helix layer. -
Hershey and Case
They created a virus called bacteriophage, which attacked living bactiria. Their virus had to inject genenict material into bacteria in order to reproduce. It consisted of protein and DNA, they used radioactive labeling to trace the DNA and sulfer to trace proteins to see what macromolecule transers genenic material. Their virus in the end injected labeled DNA into the bacteria and had transfered the virus. Proving DNA is responsable for tranformation from genetic material. -
Watson and Crick
Watson and Crick put Chargaff's and Franklins data together. after they put it together the were able to make a model of the double helix by measuring the with of the helix from Franklin's difraction and using the chart that Chargaff came up with, hence Watson and Crick proved the work of others while coming up wiith a model. -
rooselin Franklin
She cunducted X-ray difractions that in witch of DNA. She made one very big discovery but did not find out until later on when Watson and Crick took a closer look at these difractions. They saw within the fraction the double heelix for DNA. http://www.sdsc.edu/ScienceWomen/franklin.html