Samenvatting Hoofdstuk 17 - replicatie en DNA foutenherstel
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Course
Celbiologie II (EOI36A)
Institution
Katholieke Universiteit Leuven (KU Leuven)
Book
Becker\'s World of the Cell plus MasteringBiology with Pearson eText, Global Edition
dit is een samenvatting v het vak biochemie & moleculaire biologie door proffen van den eynde & derua.
met deze samenvatting haalde ik een 16 op het examen
Hoofdstuk 17 – replicatie en DNA foutenherstel
Hoofdstuk 17 – replicatie en DNA foutenherstel....................................................................................1
DNA replicatie....................................................................................................................................3
S-fase – DNA synthese...................................................................................................................3
Mogelijke mechanismen v replicatie..........................................................................................3
Begin v replicatie bij bacteriën.......................................................................................................4
Replicatie...................................................................................................................................4
Origin of replication...................................................................................................................4
Initiatie v replicatie....................................................................................................................4
Begin v replicatie bij eukaryoten....................................................................................................4
Replicatie...................................................................................................................................4
Origin of replication...................................................................................................................4
Initiatie v replicatie....................................................................................................................5
Timing v replicatie..........................................................................................................................5
DNA – polymerasen.......................................................................................................................5
DNA synthese.................................................................................................................................6
Continu & discontinu.................................................................................................................6
Bidirectioneel.............................................................................................................................6
Proeflezing.................................................................................................................................6
Key techniek : polymerase chain reaction = PCR........................................................................7
DNA – replicatie bij bacteriën........................................................................................................7
DNA-replicatie bij eukaryoten........................................................................................................9
Telomeren..................................................................................................................................9
Verkorting draagt bij tot veroudering :...................................................................................9
Telomeerherstel door telomerase..........................................................................................9
DNA schade & DNA foutenherstel...................................................................................................10
Plaats v mutaties..........................................................................................................................10
Oorzaken v mutaties....................................................................................................................10
Tautomeren..............................................................................................................................10
Fouten in repetitief DNA..........................................................................................................10
Spontane depurineringen & de-amineringen..........................................................................11
Oxidatie....................................................................................................................................11
Chemische mutagenen............................................................................................................11
Straling.....................................................................................................................................11
DNA herstelmechanismen...........................................................................................................11
1
, Fotolyase..................................................................................................................................11
Base excision repair (BER)........................................................................................................12
Thymine ipv uracil...................................................................................................................12
Nucleotide excision repair (NER)..............................................................................................12
Mismatch repair.......................................................................................................................12
Translesie synthese..................................................................................................................13
Herstel v dsDNA breuk via niet homologe end-joining (NHEJ).................................................13
Herstel v dsDNA breuk via synthesis-dependent-strand-annealing (SDSA)..............................13
Herstel v dsDNA breuk via homologe recombinatie (HR).....................................................13
Apotose....................................................................................................................................14
Key techniek : CRISPR/Cas9 genome editing................................................................................14
Homologe recombinatie en mobiele genetische elementen...........................................................15
Tijdens meiose.............................................................................................................................15
DNA uitwisseling via transposons................................................................................................15
Indeling transposons....................................................................................................................16
DNA transposons & retrotransposons......................................................................................16
DNA transposons in bacteriën..................................................................................................16
Insertie van DNA transposon leidt tot ‘target-site’ duplicatie..................................................17
Eukaryoten hebben DNA transposons & retrotransposons......................................................17
Retrotransposons.....................................................................................................................17
2
, DNA replicatie
S-fase – DNA synthese
- Generatietijd : 18-24h voor
sneldelende cellen in cultuur
- M-fase = mitose & cytokinese (30-
45 min in sneldelende cellen)
- S-fase = replicatie (6-8h) gebruik v 3H-deoxythymidine (radioactief geladen met tritium) meten
v lengte S-fase
Mogelijke mechanismen v replicatie
3 hypotheses
Experiment:
Meselson & Stahl : groei bacteriën :
eerst in 15N dan 14N medium
Scheiding zwaar & licht DNA via
densiteits-gradiënt-centrifugatie
Boven licht & onder zwaar
DNA replicatie is semi-conservatief
3e generatie : 2 banden
1: lichte band (N14-N14)
2: hybride band (N14-N15)
3 : geen zware band
3
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