lecture_13__replication_cell_division

lecture_13__replication_cell_division - Lecture13:

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Lecture 13 : Replication and cell division and the Unique Cell Cycle of Caulobacter Reading: Chapter 18.17
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Formation of the Open and Prepriming complex Transcriptional activation by RNA polymerase
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Formation of the replisome
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Leading and Lagging strand synthesis
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Step 5: Termination of Replication: ter and Tus One way passage clockwise One way passage Counter clockwise
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The Replisome
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The replisome and chromosome partitioning
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A YOU TUBE MOVIE http://www.eyeondna.com/2007/08/04/dna video molecular visualization of dna/ or http://www.youtube.com/watch?v=49fmm2WoWBs&feature=player_embedded
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Consequences of Replication 1. Taking a covalently closed two stranded helix and pulling it apart. 2 At the same time you are constructing two new two stranded helixes . 3 End result: Introduction of super coils
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What are super coils
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Topology of DNA
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DNA is a right handed helix Looking down from the top the helical turns go clockwise. Super coils are added by “underwinding” the helix, < 10.5 bases pairs/turn. During replication the two strands become unwound by DnaB helicase; this causes positive super coils to form in the front of the replication fork
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Introduction of + supercoils by replication
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When multiple forks occur, linked chromosomes can occur by recombination. The XerCD recombinase cuts the Concatomers by site specific recombination at the dif site
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Topo IV cuts and removes concatomers
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A genetic approach Fts genes control septation formation: F ilamentation, T emperature S ensitive Isolate mutants defective in septation
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Cell division genes: FtsZ : cytoplasmic proteins Ubiquitous in eubacteria, some plants as well (arabodopsis) GTPase Binds to the leading invagination of the new septum may be a homologue to eukaryotic tubulin (same ancestry) Forms a scaffolding for other proteins. FtsA
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lecture_13__replication_cell_division - Lecture13:

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