(7) Cell Cycle, Apoptosis and Cancer Flashcards
Broad overview of the cell cycle?
- Cell growth and chromosome replication
- Chromosome segregation
- Cell division
What are the stages of the cell cycle?
- The S Phase (Synthesis)
2. The M Phase (Mitosis)
Insert stages of the cell cycle here!!!
Slide 7
The Stages of the cell cycle:
What occurs in MITOSIS (M):
- Nuclear division (mitosis) at the beginning
- Cell division (cytokinesis) at the end
The Stages of the cell cycle:
What occurs in interphase?
(G1): Gap 1 phase; RNA and protein synthesis needed for DNA replication
(S): DNA synthesis
(G2): Gap 2 phase- DNA stability is checked
The Stages of the cell cycle:
What occurs during Go phase?
Occurs during POOR NUTRIENT/enviornmental conditions
–> Cells withdraw from cell cycle
*Also occurs following terminal differentiation in certain tissue types
The Stages of the cell cycle:
What are restriction points/checkpoints for?
A discrete timepoint where “errors” are checked
The Stages of the cell cycle:
___ Restriction point
___ Checkpoints
one restriction point; 3 checkpoints
The Stages of the cell cycle:
What happens if growth factors are limiting?
Growth factors are limiting
The Stages of the cell cycle:
Progression following exit from restriction point (R) is growth factor _________
independent
The Stages of the cell cycle:
G1 checkpoint
Occurs in response to:
DNA Damage
The Stages of the cell cycle:
G2 checkpoint
Purpose?
Verify complete genomic duplication
The Stages of the cell cycle:
Metaphase checkpoint
Purpose?
Ensures chromosomes attached to mitotic spindle
Cell cycle is activated by ______
growth factors
Retinoblastoma (Rb) and Cyclin activity: Describe
Rb and E2F are associated with each other. Cyclin D-CDK4 and Cyclin D-CDK6 can hyperphosphorylate RB to dissociate it from E2F…
Then, E2F can actively transcribe
____________ drives cells from G1 to S phase of the cell cycle
Rb Phosphorylation
Once E2F is actively transcribing, what does it produce?
Cyclin E: cell cycle goes from G1 to S phase
Cyclin A: S phase can occur
Retinoblastoma protein is known as a __________ protein
tumor suppressor
What are activators of cyclin-CDK activity?
-Binding of cyclin to CDK causes only PARTIAL activation
***FULL activation=CDK activating kinase (CAK)
What are inhibitors of Cyclin-CDK activity?
- p27
- WEE1
Cdk-activating kinase (CAK) and the T-Loop
What’s its role?
T-loop is a region of CDK that blocks active site
- T-loop moves out of active site after cyclin binding
- CAK phosphorylates T-loop which FULLY activates enzyme
What specific cyclins help the passage of cells through the restriction point in late G1 phase?
Cyclin D-CDK4
CyclinD-CDK6
What are the methods to regulate Cyclin-Cdk activities?
- Phosphorylation of CDK
- Binding of CKI (p27/WEE1)
- Proteolysis of cyclins
What can make a Cyclin-CDK complex fully active after being hyperphosphorylated?
CDC25 phosphatase
