* to go through each stage you need to pass checkpoints. to pass checkpoints, you need cyclin complexes present to inhibit proteins that otherwise will inhibit cell replication!
G0- Resting. Cell left cycle and stopped dividing. Cyclin C-CDK3
- G1: growth phase. cell increases protein supple and organelles, cell grows in size.
CHECKPOINT = restriction point; the cell becomes committed to entering cell cycle. DNA damage or defects can halt cell cycle in G1. Cyclin D is bound to CDK4 or CDK6 and Cyclin E is bound to CDK2. These complexes phosphorylates Rb (tumor suppressor protein made from tumor suppressor genes like p53), and Rb cant inhibit DNA replication.
**Inhibitors of Cyclin D and E: KIP/CIP inhibitors such as p21, p25, p57
**Inhibitors of Cyclin D only: INK inhibitors such as p15, p16, p18, p19
CANCER: Defective checkpoint due to p53 mutation (p53 can no longer suppress cell cycle), no apoptosis or cell death.
- S phase: Chromosomes replicated, DNA doubled. Completed ASAP bc exposed base pairs are sensitive to harmful factors. Cyclin A-CDK2 (activates DNA replication)
- G2: Cell continues to grow. G2/M
CHECKPOINT = DNA damage checkpoint, checks that all went well. Cyclin A- CDK1 and Cyclin A-CDK2 complexes activates mitosis!
Mitosis (M phase): prophase, metaphase, anaphase, telophase, cytokinesis
CHECKPOINT- mitosis checkpoint, checks if mitosis is complete Cyclin B-CDK1
*The cyclins keep the cell cycle going, CDK inhibitors are what stop it when somethings wrong.
(COMBOT- memorize cdk and inhibitors as well)
T= tumor size
N= nodal involvement
prognosis = 5 year survival
(COMBOT- memorize chart)
TIS= no invasion, stage 0, 100% prog
T1= less than 2cm, stage 1, 82% prog
T2= 2-4 cm, stage 2, 73% prog
T3= greater than 4cm, stage 3, 73% prog
T4= greater than 4cm and obvious invasion, stage 4 (it has metastasized), 19% prog
1: Very fair, pale white, often freckled.
- UV: highly sensitive, always burns never tans
- Risk: greatest risk of skin cancer
2: Fair white skin
- UV: very sensitive, burns easily, tans minimally
- Risk: high risk
3: Light brown
- UV: sensitive, burns moderately but usually tans
- Risk: high risk
4: Light brown
- UV: less sensitive, burns minimally, tans well
- at risk
5: Dark brown
- UV: minimal sensitivity, rarely burns
- Risk: rare but those that do occur are often detected at later more dangerous stage. Increased risk of low vit D levels.
6: Deeply pigmented dark brown to black
- UV: minimal sensitivity, never burns
- Risk: rare but those that do occur are often detected at later more dangerous stage. Increased risk of low vit D