Glodowski lec 10

Glodowski lec 10 - GENETICS Lecture 10 The two antiparallel...

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GENETICS Lecture 10 The two antiparallel strands proposed a nice way, as said by Watson and Crick. DNA Replication o Models Conservative Conserve original helix the entire double helix acts as template for a whole new molecule of DNA One round of replication results in 50% entirely new DNA Another round of replication results in 25% entirely new DNA With each additional replication, the number of new DNA molecules decreases Semi-Conservative One strand acts as template for another strand the two nucleotide strands unwind and each serves as a template for a new DNA molecule One round of replication results in half original DNA and half new DNA Another round of replication results in half old, half new Dispersive DNA falls apart and pieces get synthesized and come back together. Each DNA strand is some old, some new both nucleotide strands break down intro fragments which serve as templates for the new synthesis of DNA fragments, making each resulting DNA molecule interspersed with fragments of old and new DNA Always produce hybrid molecules Experiments o Meselson-Stahl (prokaryotes) To distinguish between old and new DNA, they used radioactive nitrogen. E coli + 15 N after several generations all nitrogenous bases are 15 N Take some of this e coli and put it in 14
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N. Note: 15 N is heavy and 14 N is light. Used centrifugation (equilibrium density gradient centrifugation) and noticed that e coli + 15 N stood at the bottom while those that were put in 14 N after successive replication in an 14 N medium were more at the top. The e coli with
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This note was uploaded on 01/20/2012 for the course GENETICS 380 taught by Professor Glodowski during the Fall '08 term at Rutgers.

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Glodowski lec 10 - GENETICS Lecture 10 The two antiparallel...

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