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7-DNAStructure - History Griffith 1928 Transforming...

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1 1 DNA and Chromosomes Chapter 5 Dr. Beth Dawson BIO 3, Fall 2010 San José State University 2 History Griffith, 1928 • Transforming principle http://en. wikipedia .org/wiki/File:Griffithm.jpg 3 History Griffith, 1928 Transforming principle 2 strains of Streptococcus pneumoniae – Rough, nonvirulent – Smooth, virulent • Heat killed S, nonvirulent 4 History Heat-killed S --> nonvirulent Heat-killed S + R --> virulent • How? Heat-killed S transforms R to virulent S can change R into the lethal form 5 History Griffith, 1928 Figure: http://en.wikipedia.org/wiki/Griffith%27s_experiment 6 • Griffith, 1928 Figure 5-3 Essential Cell Biology (© Garland Science 2010)
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2 7 History Avery, 1944 http://en.wikipedia.org/wiki/File:Oswald_T._Avery_portrait_1937.jpg 8 History Avery, 1944 What molecule causes transformation? – Protein, 20+ amino acids OR – DNA, 4 bases 9 History Avery, 1944 What molecule causes transformation? Figure 5-4 Essential Cell Biology (© Garland Science 2010) 10 History Hershey & Chase, 1952 https://paulingblog.wordpress.com/2009/01/02/the-martha-chase-effect/ 11 History Hershey & Chase, 1952 Which is the molecule of inheritance? Why did they use these two isotopes? 32 P 35 S 12 History Hershey & Chase, 1952 Figure 5-5b Essential Cell Biology (© Garland Science 2010) Specific result
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3 13 History Erwin Chargaff, 1951 http://history.nih.gov/exhibits/nirenberg/popup_htm/03_chargoff.htm 14 History Erwin Chargaff, 1951 Earlier hypothesis – ATCG equal amounts – chemistry suggested DNA could not carry information New equipment - chromatography and spetrophotometer 15 History Chargaff Rule 1 %A=%T, %G=%C 16 History Chargaff Rule 2 – Composition of DNA varies from one species to another
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