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Friedrich Miescher - Identification of DNA
Mieshcer began the journey of research for DNA. The scientist studied white blood cells and isolated a substance called nuclein. He concluded nuclein was found in the nucleus of a cell and was composed of the following elements: hydrogen, oxygen, nitrogen, and phosphorus. Although Mieshcer’s discoveries seemed minuscule, his work was the stimulus for a more breakthroughs concerning DNA. Had Miescher had worked with nuclein, much of the information known about DNA would not exist today. -
Erwin Chargaff - Nucleotides Rules
Chargaff’s piece to the puzzle is centered around nucleotides. Through researching with Ernst Vischer and Charlotte Green, Chargaff discovered DNA varied based on the type of organism in 1947. Also, he determined portions of bases in DNA varied with the help of Albercht Kossel and Phoebus Levene in 1949. Chargaff was so intrigued about the bases that he created a rule: the amount of purine is equal to the amount of pyrimidine per pair. -
Rosalind Franklin - Structure of DNA Pt. 1
Before Watson and Crick, Franklin arose with her knowledge of the structure of DNA. While working with college students, she used x-ray diffraction to find more information about the structure DNA. To perform this technique, Franklin had to purify the DNA first, stretch the DNA into thin fibers inside a tube, and then shoot an x-ray beam through the tube to study the findings. After studying the tube, Franklin concluded that DNA was X-shaped or the shape of a helix. -
Alfred Hershey & Martha Chase - Clarification of Genetic Material
Overtime there needed to be clarification on what exactly genetic material was. Was it protein and or DNA? Hershey and Chase created an experiment to find the answer. The scientists grew bacteriophage, with a core full of DNA and coat of protein, in phosphorus and sulfur. The goal was to observe which substance would be injected into bacterium, which would clarify the genetic material. The results stated DNA was injected into the bacterium, thus concluding DNA is the genetic material. -
James Watson & Francis Crick - Structure of DNA Pt. 2
Watson and Crick wished to gain knowledge on DNA structure. The two used Franklin’s x-ray to build a model of DNA that was composed of cardboard and wire. Using the model and previous information, it was discovered that DNA was a double helix and the nucleotides were bonded together with hydrogen bonds. Also, the scientists studied complementary base pairing, which added validity to Chargaff’s rule. To summarize, Watson and Crick validated the information from scientists about DNA was true. -
Matthew Meselson & Franklin Stahl - Replication of DNA
These scientists wanted to prove the semiconservative hypothesis was true. The hypothesis stated replicated DNA strands have DNA from new and original strands. So, Meselson and Stahl grew bacteria in heavy and light nitrogen. After combing the substances, the tubes were placed in an ultra-centrifuge and spun. The results did in fact show the replicated DNA contained strands from both the original and new strands, thus supporting the hypothesis.
