MEDRADSC 2X03 Chapter Notes - Chapter 3: Transfection, Reactive Oxygen Species, Oncogene
24 Sep 2016
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Document Summary
The final illustration in this chapter is a compilation from the literature of survival data for many types of cells. The steepest doseresponse relationship (curve a) is an average curve for mammalian cells; it is evident that they are exquisitely radiosensitive compared with microorganisms. Escherichia coli is more resistant, yeast is more resistant still, and the most resistant is micrococcus radiodurans, which shows no significant cell killing even after a dose of 1,000 gy. There are several important points to be made from this: The dominant factor that accounts for this huge range of radiosensitivities is the dna content. Mammalian cells are sensitive because they have a large dna content, which represents a large target for radiation damage. Dna content is not the whole story, however. E. coli and e. coli b/r have the same dna content but differ in radiosensitivity because b/r has a mutant and more efficient dna repair system.
