Unit2-3STUDENTS - MTI REVI EW S S ON ES I com with que e...

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MTI REVIEW SESSION come with questions Friday April 17, 2009 6-7 pm Batchelor Hall 1104
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1. Replication is bidirectional most of the time 2. E. coli has a single replication origin, eukaryotes have multiple replication origins 3. A replicon is the DNA replicated under control of one origin 4. Initiation of DNA replication requires: initiation factor helicase single-strand binding protein topoisomerase primer 5. Replication is semi-discontinuous (Okazaki) Review of Unit 2-2
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1. Primase, a specialized RNA polymerase, synthesizes required RNA primers 2. Pol I removes the RNA primers using 5’ to 3’ exo activity 3. Ligase uses ATP to seal the nick left after primer removal 4. Pol III is a multisubunit enzyme 5. Pol III uses a clamp structure to tether itself to the DNA, forming a bracelet that can’t fall off. This makes it highly processive (fast!) 6. Pol III has a low error rate and proofreading ability 7. Replication terminates in E. coli at specific Ter sites Review of Unit 2-2
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Outline for Lecture 2-3 RNA primers Replication in eukaryotes, the end problem DNA damage and mutations DNA repair mechanisms
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How do we know the primer is an RNA? No DNase DNase Fig. 20.9 RNase mutant 1 RNase mutant 2 double mutant WT cells Okazaki fragment Pimer DNA RNase-Enzyme that specifically degrades RNA DNase-Enzyme that specifically degrades DNA Okazaki fragments 1-2Kb Primer 10-12bp Primer
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5' 3' 3' 5' ori Original DNA 5' 3' 3' 5' 5' 3' 3' 5' Synthesis of lagging and leading strands (RNA primers) 5' 3' 3' 5' 5' 3' 3' 5' Primer removal 5' 3' 3' 5' 5' 3' 3' 5' Gaps filled How can the ends be completed? Challenge of Eukaryotic Termination
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Telomerase is an unusual reverse transcriptase that carries an internal RNA template for DNA synthesis
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Telomerase is an unusual reverse transcriptase that carries an internal RNA template for DNA synthesis Fig 21.31
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Types of damage -errors during DNA replication -damage from environmental agents (mutagens, UV light, X-rays, etc.) -damage due to inherent instability of DNA Why repair? Must be repaired to prevent mutation or death. Major enzymatic repair strategies proofreading during replication; mismatch repair; and excision repair.
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This note was uploaded on 06/17/2010 for the course BIOLOGY Bio 107A taught by Professor Zarate during the Spring '09 term at UC Riverside.

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Unit2-3STUDENTS - MTI REVI EW S S ON ES I com with que e...

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