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Chapter 12 Topics Chapter 12 Topics Models of Replication Prokaryotic and Eukaryotic Replication Models of Recombination: read pp 339-342
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Three Models of DNA Replication Which is correct? http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter14/animations.html#
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DATA TO SUPPORT SEMI-CONSERVATIVE MODEL
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Prokaryotic Replication Bacteria can double every 20 minutes at a rate of 1000 nucleotides/second! E.coli 4.7 million bp
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2 models of Prokaryotic Replication θ The Theta Model Rolling Pin Model Rolling Pin Model
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Theta Replication Radioactive labeled prokaryotic DNA
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Rolling Pin Model Occurs in viruses and factor F
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Prokaryotic Mechanism of Replication An: overview of E. coli replication
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Bacterial Mechanism of Replication Step 1. Initiation Step 2. Unwinding: Helicase oriC helicases Key concepts & Proteins
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Disease of Aging: Werner’s Disease In eukaryotic cells: helicase mutation has been related to “Werner’s Disease.
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Notice: Replication Bubble Forms Helper proteins Notice: Directionality
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Lagging strand Leading strand Prokaryotic DNA replicationSUMMARY
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Prokaryotes Polymerases Pol l Pol l Pol II Pol II Pol III Pol III Pol IV Pol IV Pol V Pol V The major players are: ELONGATION: step 4 repair Removes/replaces primers
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Step 5. Ligation Ligase Ligase These darn Okazaki Fragments!
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Step 6. Termination A certain DNA sequence may replication A certain DNA sequence may replication A protein may physically replication A protein may physically replication
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Lagging strand Leading strand Prokaryotic DNA replicationSUMMARY
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Animation of Elongation Nucleotide polymerization http://www.johnkyrk.com/DNAreplication.html http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter14/animations.html#
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How are mistakes avoided? By: Nucleotide selection By: Nucleotide selection By: Proofreading By: Proofreading By: Mismatch Repair By: Mismatch Repair
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Fidelity of DNA replication Only 1 mistake per billion nucleotides! Only 1 mistake per billion nucleotides!
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Eukaryotic Replication A human chromosome about 100 million bp Replication occurs in minutes to hours!
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Can you notice a difference between this replication process vs bacterial replication? Answer: Numerous replication origins.
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5’ to 3’ replication occurs in eukaryotes just like in our bacterial friends.
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Prokaryotic and Eukaryotic Replication are similar but there are some differences; these include…
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Origins “get tagged” by a replication licensing factor.
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Eukaryotic DNA Polymerases DNA Pol α DNA pol δ ß DNA pol β DNA pol ε DNA pol γ Priming & replication (RNA polymerase) Priming & replication (RNA polymerase) Replication Replication Repair & recombination Repair & recombination Repair and replication Repair and replication Mitochondrial DNA replication Mitochondrial DNA replication There are more and different DNA polymerases.
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Nucleosome Assembly Unique to eukaryotic replication process
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What happens when you reach the end of linear DNA?
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Oops a problem at the end!! http://faculty.plattsburgh.edu/donald.slish/Telomerase.html
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Telomeres and Telomerase! Are loss of telomeres related to aging?
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Or is too much telomerase activity related cancer?
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Intestinal cells Embryonic cells Cells with telomerase activity And bone marrow
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Assignment please read: pp 335- 339 The Holliday Model of DNA recombination
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