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Friedrich (Fritz) Miescher
-He did most of his work in 1869, but it wasn't published until 1871
-Fritz discovered nuclein or nucleic acids (found in the nucleus) and found that it was made of hydrogen, oxygen, nitrogen and phosphorus
-He made this discovery by taking used band aids with pus on them, removing the pus, and studying the white blood cells (he later used salmon sperm in his research instead of band aids)
-Nucleic acids are what make up DNA -
Erwin Chargaff
-In 1950 Erwin Chargaff discovered crucial facts that led to the DNA's structure
-By running experiments he discovered that the nitrogenous bases A,G,T, and C were somewhat equal
-He discovered that A is very similar and almost equal to T and same goes with G and C
-This is when he created the Chargaff's Rule: A=T and G=C
-He semi proved this because after examining both human and bacteria cells followed this rule but no one knew why
-That is how he contributed to our understanding of DNA today -
Rosalind Franklin
-In the 1950's Rosalind Franklin used X-ray diffraction to get information about the structure of DNA
-Her X-ray photos showed that the strands of DNA are twisted around each other which is known as a helix
-Rosalind showed and discovered that DNA is made of two strands from her X-ray photos
-One other clue she discovered were that the nitrogenous bases in DNA were found towards the center of the DNA molecule
-Without the X-ray photos scientists would have never discovered the structure of DNA -
Hershey and Chase
-1952 Hershey and Chase constructed an experiment to see which part of a virus infected a cell which help our understanding of DNA
-They used a bacteriophage with a DNA core and protein coat to carry out this experiment
-They divided the viruses and made either part radioactive
-After examining the infected bacteria cells, they discovered that only the DNA core of the virus was transferred into the infected bacteria cell
-They discovered and confirmed that DNA is the molecule of heredity -
Watson and Crick
-In 1953 Watson saw a copy of Franklin's X-ray photo
-After trying for many years to build a model of DNA Watson and Crick came to realize what they were missing when Watson explained Franklin's X-ray photo
-They had discovered that the two strands of DNA are "antiparallel" and due to this the nitrogenous bases on both strands meet in the center of the molecule
-They also discovered that the model is held by hydrogen bonding
-With this information they completed the current DNA model today -
Meselson & Stahl
-Their research paper was published in 1958
-The discovery was made through various experiments that had lots of 'delightfully clean data.' But I was unable to find what the experiments consisted of other than a lot of pipetting DNA. They also had 3 theories of how DNA was replicated: semi conservative, conservative, and dispersive. Of the 3, only semi-conservative proved correct
-Their research helped solidify the discovery of the double helix by James Watson and Francis -
A.D. Hershey and Martha Chase
-1952 Hershey and Chase used bacteria to conduct their experiment
-They used bacteriophage that had a DNA core and protein coat to see which part entered bacteria cells after infecting the cells
-They made the viruses radioactive
-One radioactive tag on the protein coat and another one on the DNA core
-While examining the infected bacteria, they discovered that the bacteria cells had received the DNA core only
-Hershey and Chase discovered and confirmed that DNA is the molecule of heredity -
Bibliography
-23 Jan. 2017, lebbeuswoods.files.wordpress.com/2010/08/watson-crick-2.jpg. -“The Hershey and Chase Experiments.” The Hershey and Chase Experiments, 19 Apr. 2014, biology-pages.info/H/Hershey_Chase.html. -“Image of Erwin Chargaff.” Image of Erwin Chargaff, 23 Jan. 2017, upload.wikimedia.org/wikipedia/en/thumb/a/a1/Erwin_Chargaff.jpg/220px-Erwin_Chargaff.jpg. -Mccarthy, Eugene M. “Erwin Chargaff.” Biography - Famous Biologists, www.macroevolution.net/erwin-chargaff.html. -
Bibliography Continued
-Miller, Kenneth R., and Joseph S. Levine. Biology. Foundation, Upper Saddle River, New Jersey, Pearson Curriculum Group, 2010. -Pray, Leslie A. “Discovery of DNA Structure and Function: Watson and Crick.” Nature.com, Macmillan Publishers, 2008, www.nature.com/scitable/topicpage/discovery-of-dna-structure-and-function-watson-397. -“Rosalin Franklin and Her X-Ray Photo.” Rosalin Franklin and Her X-Ray Photo, 23 Jan. 2017, jabrooks01.blogs.wm.edu/files/2010/10/rosalind-franklin.gif. -
