Chapter_16_Outline - Ch 16 The Molecular basis of...

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Ch. 16: The Molecular basis of Inheritance I. DNA as the Genetic Material A. Researchers originally thought protein was the genetic material because biochemists had identified them as a class of macromolecules with great heterogeneity and specificity of function, essential requirements for the hereditary material. Moreover, little was known about nucleic acids, whose physical and chemical properties seemed far too uniform to account for the multitude of specific inherited traits exhibited by every organism. B. i. Frederick Griffith- studied transformation in Streptococcus pneumoniae ii. Oswald Avery, Maclyn McCarty, and Colin MacLeod- purified various chemicals from the heat- killed pathogenic bacteria & tried to transform live nonpathogenic bacteria with each chemical; the transforming agent was DNA. iii. Alfred Hershey and Martha Chase- performed experiments showing that DNA is the genetic material of a phage known as T2. iv. Erwin Chargaff- analyzed the base composition of DNA from a number of different organisms; reported that DNA composition varies from one species to another (1947). C. Watson saw Rosalind Franklin’s X-ray diffraction images of DNA and noted that DNA was in helical shape; he also determined the width of the helix and the spacing of the nitrogenous bases along it. Watson and Crick then began building models of a double helix that would conform to the X-ray measurements and what was then known about the chemistry of DNA using molecular models made of wire. D.
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This note was uploaded on 06/15/2010 for the course FDST 4080 taught by Professor Pegg during the Spring '10 term at UGA.

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Chapter_16_Outline - Ch 16 The Molecular basis of...

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