1. Cell Cycle and Mitosis 9.1 Cell Cycle

2. What is the cell cycle?  Repeating series of events  Five stages  Interphase (3 parts)  G 1  S  G 2  M phase (2 parts)  Mitosis  Cytokinesis

3. What happens in Interphase?  G 1  Normal growth  Recovery from last mitotic division  S  Replication of chromatids  G 2  Synthesis of proteins for mitosis

4. Cell Cycle and Mitosis 9.2 M phase: Mitosis and cytokinesis

5. What happens during the M phase?  Mitosis  Prokaryotes undergo binary fission instead  Cytokinesis

6. What is a chromosome?  Length of DNA with genes and noncoding regions  Highly condensed version of chromatin  Heterochromatin vs. euchromatin

7. What is mitosis?  Division of nuclear material  Duplicated chromosomes are split  This creates unduplicated chromosomes  Chromosome terminology  Sister chromatids  Kinetechore  Centromere  Diploid (2n) vs. haploid (1n)

8. What are the stages of mitosis?  Prophase  Prometphase  Metaphase  Anaphase  Telophase

9. What happens in prophase?  Nuclear envelope disappears  Centrioles move apart  Nucleous disappears  Chromatin condenses to form chromosomes  Recall that these are duplicated

10. What happens during prometaphase?  Kinetechores appear  Spindles attach  Polar spindle fibers extend and overlap

11. What happens during metaphase?  Duplicated chromosomes align along metaphase plate

12. What happens during anaphase?  Sister chromatids pulled apart  Chromosomes are now unduplicated

13. What happens during telophase?  Reverse of prophase  Cleavage furrow develops in animal cells

14. What is the second part of the M phase?  Cytokinesis  Cytoplasmic division  Animal cells  Contractile ring  Plant cells  Cell plate

15. Cell Cycle and Mitosis 9.3 Cell cycle control and cancer

16. Why do cells undergo mitosis?  Repair and replacement  Apoptosis of somatic cells  blebbing  Stem cells  Serve as reservoir for replacing old cells

17. What controls the cell cycle?  Checkpoints  G 1  Apoptosis if DNA is damaged  G 2  M

18. What is cancer?  Uncontrolled cell growth  Characteristics  Neoplasms (tumors)  Benign vs. malignant  Angiogenesis  Metastasis  Abnormal nuclei  Undifferentiated (anaplasia)  Lack contact inhibition  No apoptosis

19. How does cancer occur?  Mutations of cell repair genes  Activation of telomerase  Mutations of either/both  Proto-oncogenes  Become oncogenes  Tumor suppressor cells

20. What are proto-oncogenes?  “gas pedal” of cell division  Mutated  oncogene  Examples  ras genes  rasN (leukemia)  BRCA1

21. What are tumor suppressor genes?  Brake pedal of cell division  If mutated  loss of cell cycle control  Examples  p53 gene  RB gene