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Unformatted text preview: But lets go back in historyhow did people answer the fundamental question: What is the chemical nature of the genetic material? S bacteria = pathogenic (virulent) R bacteria = non-pathogenic (avirulent) 1928: Fredrick Griffith and colleagues Figure 11-1 Genetic Transformation of Non-virulent bacteria Conclusion of the Griffith Experiment: Whatever the genetic material is, it survived heating and could be transferred into R cells, stably converting them into S cells The big question remains: What component of S cell debris caused the conversion of R cells into S cells?????? Figure 11-2 Genetic Transformation by bacteria (Avery et al., 1944) Conclusion of the 1944 Avery experiment : DNA is the genetic material.at least for bacteria! ..not terribly well received. More evidence accumulating in favor of DNA being the genetic material DNA found only in the nucleus, and the nucleus is intimately involved in heredity; Amount of DNA in all cells of an organism is constant, except for sperm and egg, where it is half of other cells; Under normal circumstances, DNA is never degraded; protein is made and degraded in the normal course of events .this is all indirect evidence.we need some direct data!...
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- Summer '09