Discovery of Genetic Material

Discovery of Genetic Material - dead bacteria w...

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Discovery of Genetic Material Hammerling experiment - determined where cells kept hereditary material used Acetabularia cells, found that hereditary material in foot area transplanted different parts of A. mediterranea and A. crenulata parts eventually developed according to the hereditary material in foot area (intermediate head formed at first due to remaining RNA left in stalk) transplantation experiments - added support that nucleus contained hereditary material Thomas King/Robert Briggs - transplanted nuclei from frog cells o cells wouldn’t develop w/o nucleus o showed that nuclei contained the information needed to direct development F. C. Steward - mixed fragments of carrot tissue w/ liquid growth medium o showed that single cells can form entire, mature plants o totipotent - containing full set of hereditary instructions Griffith experiment - discovered transformation found that S. pneumoniae bacteria could only infect w/ polysaccharide coating
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Unformatted text preview: dead bacteria w/ polysaccharide coating mixed w/ live bacteria w/o polysaccharide coating to form live bacteria w/ polysaccharide coating • transformation- transfer of genetic material from one cell to another Avery experiments- found the “transforming principle” from Griffith ’s experiments • removed nearly all of the protein in S. pneumoniae, but transformation still occurred • purified mixture contained elements close to that of DNA, had same density • taking out lipids/proteins didn’t stop transformation • DNA-digesting enzyme DNase stopped all transformations • showed that DNA provided hereditary material for bacteria Hershey-Chase experiment- studied bacteriophages, viruses that infect bacteria • viruses - contain DNA or RNA surrounded by protein coat o causes cells to produce so many viruses that it bursts (lyses) • used radioactive isotopes to track DNA and protein coat • showed that DNA caused changes in cells, not protein...
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