DNA Replication & Cell Cycle [email protected]
medpathwaymcat Med-pathway The Cell Cycle
G0
M
G1 G2
(START) S Growth Factors Cyclin Dependent Kinases
Phosphorylation of Targets
D B Cdk Cdk M
G1
G2
S E Cdk Cyclin Dependent Kinases
Cyclin E Cdk 1
Cyclin D Concentration of Cyclin of Concentration
G1 S G2 Mitosis MITOSIS
1 2
4 3
Centrosome
5 6 ORIGINS OF REPLICATION
DnaA
ORIGIN oriC
DnaA DnaA
5’ 3’ 3’ 5’
The Replicator Hypothesis The Hayflick Limit Finite Replicative Capacity of Cells
Senescence GROWTH
TIME Cellular Transformation Crisis (Transformation)
Senescence GROWTH
TIME TELOMERES
The End Replication Problem
5’ GGGTTAGGGTTAGGGTTAGGGTTAGGGTTAGGGTTA3’ 3’ CCCAAT CCCAAT CCCAAT 5’ TELOMERES
The End Replication Problem
5’ GGGTTAGGGTTAGGGTTAGGGTTAGGGTTAGGGTTA 3’ CCCAAT CCCAAT CCCAAT 5’ AAUCCCAAU 3’ 5’ Telomerase Cellular Transformation Crisis (Transformation) Reactivation of Telomerase
Senescence GROWTH
TIME Meselson Stahl Experiment
1. Grow Cells in 15N media 2. Transfer to 14N media and Monitor cell divisions
Time
Semi Conservative Replication
14N 15N 15N/14N DNA Replication Fork
Kornberg’s Purification of DNA Polymerase
Semi-conservative DNA Replication DNA Polymerization
DNA Chain Terminators Sanger DNA Sequencing 1. 2.
Dideoxy H Nested X
H DNA Structure & Mutation
3’
5’ 5’ to 3’ 5’ G C 5’ to 3’
3’
T A
T G
DNA Mismatch DNA Structure & Mutation: Tautomers
(LACTAM) (LACTIM)
1.0 % Tautomers & Mutations DNA Replication & DNA breaks
Primer “NICK” Fixing The DNA Breaks (S/G2) DSB Repair
HR (S/G2)
5′ 3′ 5′ 3′ 3′ 5′ 3′ 5′ 5’ to 3’ exonuclease
5′ 3′ 5′ 3′ 3′ 5′ 3′ 5′ HO
D loop formation
HO
Branch migration, Resolution Fixing The Break In G1 NHEJ
D Cdk
p53 is a tumor suppressor Fixing The DNA Breaks
DSB Repair
NHEJ (G1) HR (S/G2)
5′ 3′ 5′ 3′ 3′ 5′ 3′ 5′ 5’ to 3’ exonuclease
5′ 3′ 5′ 3′ 3′ 5′ 3′ 5′ HO
+ D loop formation
Rad51 BRCA HO
Branch migration, Resolution Translocations Drive Oncogenesis
Burkitt Lymphoma BCR-ABL
9 Philadelphia 22 Chromosome
+ +
BCR BCR-ABL (Tyrosine Kinase)
ABL Chronic Myeloid Leukemia (CML)