1. Cell Cycle Guided Reading Questions Review Stages of Mitosis Animation

2. Mitosis Promoting Factor (MPF) – 2 subunits: 1.Protein kinase – [constant]; catalyzes phosphorylation **the engine that drives cell cycle!** 2.Cyclin – [increases]; binds to kinase Cdk **Dimer = activated MPF

3. Activated MPF initiates production of several proteins: a)Chromosomal proteins – initiates M phase b)Lamins –initiates breakdown of nuclear envelope c)Microtubule associated proteins – play a role in mitotic spindle development d)Enzyme degrading cyclin – deactivate MPF

4. sufficient nutrients GF’s present DNA undamaged Cell Cycle Regulated by 3 checkpoints G1 Checkpoint **passage of this Checkpoint means irreversible commitment to division** interphase

5. G2 Checkpoint DNA undamaged Environmental conditions good? Cell size?

6. Metaphase Checkpoint (spindle checkpoint) Cell Cycle Control Animation **At all phases, phosphorylation & dephosphorylation of kinase component of the MPF can activate & inactivate activity** APC? Chromsomes attached to spindle at metaphase plate?

7. Healthy Cells ~ normal growth ~ GF’s ~ Adhere to nearby cells ~ Regulation ~ p53 gene Cancerous Cells ~ Rapid growth/division ~ invasive ~ damage healthy cells ~ No controls Both ~ grow ~ divide

8. Cell Cycle Pathways **Growth factors act as social controls** In normal cells: GF’s rcvd from surrounding cells bind to receptors induce cyclin production cell division initiated

9. In abnormal cells: G F’s not needed for growth/division p athway disrupted o verproduction of cyclin ( ↑ division) defective “brake proteins (ex: p53)” can not suppress growth → tumors benign malignant (metastasis) Cancerous cells animation

10. Cancer is a disease of the cell cycle impacted by various factors (age, genetics, environment; oncogenes/proto-oncogenes)

11. The environment: Some environmental agents associated with cancer are: Viruses Tobacco smoke Food Radiation Chemicals Pollution

12. Viruses Viruses—mostly in the form of DNA viruses—have been causally linked to cancer. Human papillomaviruses (HPV) — primarily types 16 and 18  sexually transmitted  linked to cervical cancer > 25 other types of papillomaviruses linked to cancer Hepatitis B & C — linked to liver cancer Human immunodeficiency virus (HIV) — linked to Kaposi's sarcoma and lymphoma Retroviruses (carry genetic info in RNA) — linked to cancers in animals other than humans

13. Tobacco smoke Associated with 50% - 60% of all cancer deaths Linked to cancers of: lung, upper respiratory tract, esophagus, bladder, pancreas Likely cause of stomach, liver, kidney, colon, and rectal cancer

14. Pollution Difficult to document as a contributor to human cancer…. … long-term exposure to high levels of air pollution may increase lung cancer risk by as much as 25%.