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CHAPTER 16 BIOLOGY READING FREDERICK GRIFFITH’S EXPERIMENT -when he killed the pathogenic bacteria with heat and then mixed the cell remains with living bacteria of the nonpathogenic strain, some of the living cells became pathogenic -inherited by all the descendants of the transformed bacteria - transformation - change in genotype and phenotype due to the assimilation of external DNA by the cell EVIDENCE THAT VIRAL DNA CAN PROGRAM CELLS bacteriophages - viruses that infect bacteria ADDITIONAL EVIDENCES -DNA nucleotides vary in composition percentages between different organisms -#of adenines=#of thymines, #of guanines=#of cytosines DNA STRUCTURE double helix - presence of two strand -sugar phosphate backbones were on the outside of the double helix -hydrophobic nitrogenous bases in the molecule’s interior -purines= single ring, pyrimidines= double ring -pyrimidine always pair with purine -A forms 2 H bonds with T; G forms 3 H bonds with C DNA REPLICATION semiconservative model - the strands seperate, each acting as a templet to form a new conplementary strand -1/10 billion nucleotide errors occur origin of replication - the site where DNA replication begins -bacterial chromosome has single origin- creates bubble at on the origin
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This note was uploaded on 07/14/2009 for the course BILD BILD1 taught by Professor Bever during the Spring '08 term at UCSD.

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