Molecular Genetics 1

Molecular Genetics 1 - Francke Lecture 1 Oct.22,2008 Human...

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Oct.22,2008 HumBio2A.Molecular Genetics I 1 Francke Lecture 1 10/21/08 HumBio 2A. Molec.Genetics I 1 Molecular Genetics I DNA: structure, and packaging into chromosomes Human Biology 2A Dr. Uta Francke Department of Genetics, SUMC ufrancke@stanford.edu 10.22.08 10/21/08 HumBio 2A. Molec.Genetics I 2 • What is the evidence that the gene is DNA? • What is the structure of DNA? • How is DNA packaged into chromatin? DNA 10/21/08 HumBio 2A. Molec.Genetics I 3 Frederick Griffith (in 1920s), working with two strains of Streptococcus pneumoniae determined that a transforming principle from dead cells of one strain produced a heritable change in the other strain. How was the role of DNA discovered?
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Oct.22,2008 HumBio2A.Molecular Genetics I 2 Francke Lecture 1 10/21/08 HumBio 2A. Molec.Genetics I 4 Griffith’s Transformation Experiment Smooth [S] and lethal Rough [R] and benign Two strains of Streptococcus pneumoniae Inject into mice Living S strain Living R strain Mouse dies Living S strain found in heart Mouse healthy No bacteria found in heart Mouse healthy No bacteria found in heart Mouse dies Living S strain found in heart Inject into mice Inject into mice Heat S strain (kil s bacteria) Mix heat-kil ed S strain with live R strain bacteria The virulence trait (and “smoothness”) were transferred to the R strain from dead S strain bacteria, and the properties were passed on permanently (i.e. inherited) in the bacteria produced in mice. A chemical substance was transferred! 10/21/08 HumBio 2A. Molec.Genetics I 5 How do you identify the transforming substance? Oswald Avery: Made extracts from S strain bacteria and selectively destroyed different molecules: RNA, protein or DNA Found that if DNA was destroyed, the transforming principle was lost 10/21/08 HumBio 2A. Molec.Genetics I 6 Genetic Transformation by DNA Conclusion: Because only DNase destroyed the transforming substance, it must be DNA They purified the substance and analyzed it, and concluded that it was indeed DNA without detectable protein
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Oct.22,2008 HumBio2A.Molecular Genetics I 3 Francke Lecture 1 10/21/08 HumBio 2A. Molec.Genetics I 7 1944: Avery, MacLeod and McCarty Oswald Avery Colin MacLeod Maclyn McCarty
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This note was uploaded on 11/08/2009 for the course HUMBIO 2A taught by Professor Boggs,c;durham,w during the Spring '08 term at Stanford.

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Molecular Genetics 1 - Francke Lecture 1 Oct.22,2008 Human...

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