Chapter 6 Molecular biology of DNA Replication and Replication and Recombination Overview Introduction Semiconservative replication of double- stranded DNA Modes of replication Unwinding, stabilization and stress relief Initiation by a primosome complex Chain elongation and proofreading Discontinuous replication of the lagging strand Terminator sequencing of DNA Molecular mechanisms of recombination “It didn’t escape our attention that …” Problems of initiation, elongation, incorporation errors Initiation: Replicons & origins of replication Replicons & origins of replication RNA primers El ti Elongation: 5’ to 3’ only Leading versus lagging strand Errors or incorporation Errors or incorporation Proofreading
12
Embed
Molecular biology of DNA Replication and Recombination · Molecular biology of DNA Replication and ... Theta replication of circular chromosomes Rolling circle replication ... replication
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Chapter 6
Molecular biology of DNA Replication and Replication and Recombination
OverviewIntroductionSemiconservative replication of double-pstranded DNAModes of replicationUnwinding, stabilization and stress reliefInitiation by a primosome complexChain elongation and proofreadingDiscontinuous replication of the lagging strandp gg gTerminator sequencing of DNAMolecular mechanisms of recombination
“It didn’t escape ourpattention that …”
Problems of initiation, ,elongation, incorporation errors
Initiation:Replicons & origins of replicationReplicons & origins of replicationRNA primers
El tiElongation:5’ to 3’ onlyLeading versus lagging strand
Errors or incorporationErrors or incorporationProofreading
OverviewIntroductionSemiconservative replication of double-pstranded DNAModes of replicationUnwinding, stabilization and stress reliefInitiation by a primosome complexChain elongation and proofreadingDiscontinuous replication of the lagging strandp gg gTerminator sequencing of DNAMolecular mechanisms of recombination
Meselson-Stahl experiment
Equilibrium density gradient q y gcentrifugation
Semi-conservative replication pof DNA in chromosomes
Semi-conservative replication pof DNA in chromosomes Overview
IntroductionSemiconservative replication of double-pstranded DNAModes of replicationUnwinding, stabilization and stress reliefInitiation by a primosome complexChain elongation and proofreadingDiscontinuous replication of the lagging strandp gg gTerminator sequencing of DNAMolecular mechanisms of recombination
Theta replication of circular pchromosomes
Theta replication of circular pchromosomes
Theta replication of circular pchromosomes Rolling circle replication
Rolling circle replicationMultiple origins and bidirectional p greplication in eukaryotes
Multiple origins and bidirectional p greplication in eukaryotes
Replication speed and duration p pin pro- and eucaryotes
Eukaryotes:10-100 nt/sec => days / chr (10^7) 10-100 nt/sec => days / chr. (10 7) => multiple origins of replication
> 5 10 h=> 5-10 hrs
Prokaryotes:1,500 nt / sec => 30 min / genome
20 min. generation inertval !g
OverviewIntroductionSemiconservative replication of double-pstranded DNAModes of replicationUnwinding, stabilization and stress reliefInitiation by a primosome complexChain elongation and proofreadingDiscontinuous replication of the lagging strandp gg gTerminator sequencing of DNAMolecular mechanisms of recombination
Unwinding, stabilization and g,stress relief
Unwinding, stabilization and g,stress relief Overview
IntroductionSemiconservative replication of double-pstranded DNAModes of replicationUnwinding, stabilization and stress reliefInitiation by a primosome complexChain elongation and proofreadingDiscontinuous replication of the lagging strandp gg gTerminator sequencing of DNAMolecular mechanisms of recombination
OverviewIntroductionSemiconservative replication of double-pstranded DNAModes of replicationUnwinding, stabilization and stress reliefInitiation by a primosome complexChain elongation and proofreadingDiscontinuous replication of the lagging strandp gg gTerminator sequencing of DNAMolecular mechanisms of recombination
Chain elongation and gproofreading
ElongationProcaryotes: polymerase III Procaryotes: polymerase III holoenzyme (2 x DNA polymerase III + > 7 p oteins)+ > 7 proteins)Eucaryotes: polymerase deltaReplication errors: rate and causeProofreading exonuclease 3’ to 5’ Proofreading exonuclease 3 to 5 activity
5’ to 3’ chain elongation Proofreading
Proofreading precludes 3’ to 5’ g pelongation Overview
IntroductionSemiconservative replication of double-pstranded DNAModes of replicationUnwinding, stabilization and stress reliefInitiation by a primosome complexChain elongation and proofreadingDiscontinuous replication of the lagging strandp gg gTerminator sequencing of DNAMolecular mechanisms of recombination
Discontinuous replication of the plagging strand
Leading vs lagging strand, Okazaki fragmentsfragmentsJoining of the precursor fragments
Procaryotes:Procaryotes:Pol I (5’ to 3’ exonuclease activity)+ ligaseg
EucaryotesReplication Protein APol deltaLigase
Leading vs lagging strand, g gg g ,Okazaki fragments
Leading vs lagging strand, g gg g ,Okazaki fragments
DNA joining of precursor j g pfragments - procaryotes
5’ to 3’ exonuclease activity of polII
Removes RNA primerGenerates 5’ P end (vs 5’ PPP end of Generates 5’ P-end (vs 5’ PPP-end of primer)
li+ ligase
DNA joining of precursor j g pfragments - eucaryotes Overview
IntroductionSemiconservative replication of double-pstranded DNAModes of replicationUnwinding, stabilization and stress reliefInitiation by a primosome complexChain elongation and proofreadingDiscontinuous replication of the lagging strandp gg gTerminator sequencing of DNAMolecular mechanisms of recombination
IntroductionSemiconservative replication of double-pstranded DNAModes of replicationUnwinding, stabilization and stress reliefInitiation by a primosome complexChain elongation and proofreadingDiscontinuous replication of the lagging strandp gg gTerminator sequencing of DNAMolecular mechanisms of recombination
Recombination: double-strand break and repair model
Recombination: double-strand break and repair model
Recombination: Mismatch repair and gene conversion