M1 L2

Question 1

3 ways replication is controlled

Answer 1

kinases, licencing/unlicencing and checkpoint proteins

Question 2

What kinases are involved in controlling replication

Answer 2

DDK
Sld1
S-CDK

Question 3

DDK

Answer 3

P helicase to activate them

Question 4

S-CDK

Answer 4

P sdl1 protein which comes in after DDK has been P. Also P polymerase –> MCM10 can then come in

Question 5

What phase of the cell cycle does licencing/unlicencing occur in

Answer 5

licencing happens in G phase, unlicencing happens in S phase

Question 6

How is Licencing and unlicening controlled

Answer 6

CDK kinase activity (P) => Cdc6 degraded and downregulated. Cdt1 abd MCM exported from nucleus

Question 7

Describe Ori sites in yeast and compare to ori sites in higher eukaryotes

Answer 7

• 100-200 bp in yeast, 30-100 bp in eukaryotes
• far apart in eukaryotes
• has an essential AT rich region required for ori function but eukaryotes don’t although ori still needs to be AT rich

Question 8

What 3 things determine Ori sites

Answer 8

chromatin structure
nucleosome position
transcriptional activity

Question 9

Events at the replication origin G1 phase

Answer 9

cdc6 comes in to complete ORC. MCM1-7 and cdt1 come in. cdc6 and cdt1 come off

Question 10

Events at the replication origin S phase

Answer 10

cdc45 and GINs come in to make helicase + pol e to make PIC
MCM10 kickstarts replication
RPA binds ssDNA
Orc leaves and pol a and d come in

Question 11

cdt1 over expression leads to..

Answer 11

more MCM complexes being able to bind to the DNA - too many copies - tumorigenesis

Question 12

Examples of diseases caused by mutations in proteins that control replication

Answer 12

1. Meier-Gorlin syndrome (mutations in ORC1)
2. cdt1 and cdt6 overexpressed in some tumours

Question 13

what controls licencing and unlicencing

Answer 13

CDK kinase activity and transcriptional regulation