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Unformatted text preview: Chapter 10 The Search for the Genetic Material o Principal Characteristics of Hereditary Info stable info about structure, function, dvlpmnt, & reproduction replicate accurately capable of change o Miescher discovered nucleic acid, nuclein = chromatin - 1869 o Griffiths Transformation Exp (1928) Streptococcus pneumoniae Mouse, smooth & rough bact, transforming principle = agent responsible for change in genetic material o Averys Transformation Exps (1930s-40s) Streptococcus pneumoniae Cells treated w/ some sort of macromolecule-ase no transformants w/ DNAase criticized b/c nucleic acids isolated from bact were contaminated by prot o Hershey-Chase Bacteriophage Exps (1953) T2 bacteriophage w/ E. coli radioactively labeled DNA & protein on virus proved DNA was genetic material o Discovery of RNA as Viral Genetic Material Gierer & Schram (1956)TMV infction only whn ribonclse not treated w/ RNA-ase Fraenkel-Conrat & Singer (1957) different TMV RNA hybrid w/ opposite proteins progeny is w/e type of RNA it is Composition & Structure of DNA & RNA o General nucleosides: pentose sugar, nitrogenous base nucleotide: w/ phosphate group purines 9-membered double-ring; AG pyrimidine 6-membered single-ringed; CUT base attached to 1 C phosphate attached to 5 C linked by phosphodiester bonds strong bonds gives polarity o DNA Double Helix Base Composition Studies (Chargaff) Chargaffs Rules X-Ray Diffraction Studies (Franklin & Wilkins) - Crystallography X-ray diffraction: beam of parallel x-rays aimed at molecules beam broken up by atoms in a pattern diffracted xrays recorded on a photographic plate regular 0.34 nm & 3.4 nm intervals; symmetry Linus Pauling found Right-handed alpha helix structures in proteins Watson & Cricks Model...
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