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Chapter 12Chapter 12TopicsTopics
Models of Replication
Prokaryotic and Eukaryotic Replication
Models of Recombination: read pp 339-342
Three Models of DNA Replication Which is correct?
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter14/animations.html#
Prokaryotic ReplicationProkaryotic Replication
Bacteria can double every 20 minutes at a rate of 1000 nucleotides/second!
E.coli 4.7 million bp
2 models of Prokaryotic 2 models of Prokaryotic ReplicationReplication
θθThe Theta Model The Theta Model
Rolling Pin ModelRolling Pin Model
Prokaryotic Mechanism of Prokaryotic Mechanism of ReplicationReplication
An: overview of E. coli replication
Animation of ElongationAnimation of Elongation
Nucleotide polymerization
http://www.johnkyrk.com/DNAreplication.html
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter14/animations.html#
Bacterial Mechanism of Replication
Step 1. Initiation
Step 2. Unwinding: Helicase
oriC
helicases
Key concepts & Proteins
Prokaryotes PolymerasesProkaryotes Polymerases
Pol l Pol l
Pol IIPol II
Pol IIIPol III
Pol IVPol IV Pol VPol V
The major players are:The major players are:
ELONGATION: step 4
repair
repair
Removes/replaces primers
Step 6. TerminationStep 6. Termination
A certain A certain DNA sequenceDNA sequence may may replicationreplication
AA proteinprotein may physically replication may physically replication
How How areare mistakes avoided? mistakes avoided?
By: Nucleotide selectionBy: Nucleotide selection
By: ProofreadingBy: Proofreading
By: Mismatch RepairBy: Mismatch Repair
Fidelity of DNA replicationFidelity of DNA replication
Only 1 mistake per billion nucleotides! Only 1 mistake per billion nucleotides!
Eukaryotic ReplicationEukaryotic Replication
A human chromosome about 100 million bp Replication occurs in minutes to hours!
Can you notice a difference between this replication process
vs bacterial replication?
Answer: Numerous replication origins.
Prokaryotic and Eukaryotic Prokaryotic and Eukaryotic Replication are similar but Replication are similar but
there are some differences; there are some differences; these include…these include…
Eukaryotic DNA PolymerasesEukaryotic DNA Polymerases
DNA Pol DNA Pol αα
DNA polDNA pol δδ
ß DNA pol DNA pol ββ
DNA pol DNA pol εε
DNA pol DNA pol γγ
Priming & replication Priming & replication (RNA (RNA polymerasepolymerase
ReplicationReplication
Repair & recombinationRepair & recombination
Repair and replicationRepair and replication
Mitochondrial DNA replicationMitochondrial DNA replication
What happens when you reach What happens when you reach the end of linear DNA?the end of linear DNA?
Disease of Aging: Werner’s Disease of Aging: Werner’s DiseaseDisease
Related to mutated helicase; Why would this cause an error in DNA replication?
Assignment please read: pp Assignment please read: pp 339-342339-342
The Holliday Model of DNA recombination
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