Chapters 10 & 11 Cell Division Chapter 10: Cell cycle, Mitosis & Cancer Not responsible for:

1. Chapters 10 & 11 Cell Division Chapter 10: Cell cycle, Mitosis & Cancer Not responsible for: Figure 10.3 & related text on proteins that control chromosome separation and septum formation 10.7 Control of the cell cycle. This section covers more of the molecular details than you will be responsible for; however, we will cover the concept of cell cycle checkpoints, oncogenes and tumor suppressor genes as related to cancer Cell Reproduction

2. Why is it important to understand the processes of cell replication? Diversity & evolution Cancer Birth defects Reproductive biotechnology Basal cell carcinoma eukaryotic prokaryotic Cell Reproduction

3. What are the characteristics of cell division in Prokaryotes? Simpler structure No nucleus Single chromosome Binary fission Cell Reproduction

4. Chromosome structure in eukaryotes Structure of chromosomes … in nondividing cells … in dividing cells Supercoiling Cell Reproduction

5. What are homologous chromosomes? Homologous Chromosomes: -- one derived from each parent -- possess same genes, although genetic information in gene may be different = “alleles” How many homologous chromosomes do different organisms possess? humans: 2N = 46 N= haploid # of chromosomes goldfish: 2N=94 crayfish: 2N = 200 Autosomes vs sex chromosomes Cell Reproduction

6. What is the cell cycle? What are the stages and events? Mitosis G1 G0 S G2 Cell Reproduction

7. What are the steps of mitosis? When does mitosis occur? What are the stages of mitosis? prophase prometaphase metaphase anaphase telophase Cytokinesis Animal cell mitosis Cell Reproduction

8. McGraw-Hill mitosis What happens during prophase? Chromosome condensation Spindle apparatus Centrosomes What happens during prometaphase? Nuclear membrane Spindle attachment Kinetochores kinetochore Cell Reproduction

9. …Metaphase …Anaphase Filaments ‘pull’ and “push’ Cell Reproduction

10. Telophase and cytokinesis What happens during telophase? What causes cytokinesis to occur? Does cell division in plants and animals differ? Plant cell mitosis Cell Reproduction

11. Homework assignment: 5 points: due next class For a cell where 2N=6, draw a series of diagrams showing the chromosomes moving through the stages of mitosis. In one of the diagrams clearly label: -- a pair of homologous chromosomes -- two sister chromatids -- spindle fibers -- centrosomes and -- position of a kinetochore Label all stages (prophase, prometaphase, metaphase, anaphase and telophase) Make diagrams large, clear and neat Advanced artistry is not required, but drawings of supercoiled chromosomes and spindle fibers must show reasonable effort to accurately represent these structures. x not Cell Reproduction

12. Why learn about the cell cycle? • Cancer • Biotechnology Basal cell carcinoma Cell Reproduction

13. Embryonic stem cells could be used to repair tissue and organ damage Must culture and induce differentiation Cell Reproduction

14. Cancer often begins with cells that lose control over cell replication -- mutations accumulate over time -- an evolutionary process Some “oncology” terminology Benign tumor Malignant tumor Metastasis Primary vs secondary tumor Cancer Cell Reproduction

15. Mutations altering 3 key cell properties and “set the stage” for metastasis  Mutations that trigger cell proliferation  activation of “Oncogenes”  Mutations that disable DNA error detection (and repair)  disabling of “Tumor suppressor proteins”  Mutations that confer immortality Cell Reproduction

16. Tumor suppressor proteins are ‘Gatekeepers’ and ‘Caretakers’ of the cell Stop Go Die Cell Reproduction

17. When mutations to Tumor Suppressor Genes can disable the corresponding Tumor Suppressor Proteins . . . Cells divide when they shouldn’t Cells do not die when they should Cells progress toward metastasis Cell Reproduction

18. In some breast cancers, Epidermal Growth Factor (EGF) receptor is mutated Normal gene = “proto-oncogene” Mutated gene = “oncogene” Cell Reproduction

19. Chapter 11 Sexual Reproduction and Meiosis Meiosis and Gametes

20. When and where does meiosis occur in humans? Why is meiosis necessary? “reductive division” Meiosis and Gametes

21. What are the stages of Meiosis? Meiosis I vs Meiosis II Prophase I Metaphase I Anaphase I Telophase I McGraw-Hill Meiosis Meiosis unique features Meiosis and Gametes

22. How does Prophase I differ from Prophase of Mitosis? • Bivalents form -- “synapsis” -- homologous chromosome pairs 2) Crossing over occurs -- exchange of DNA segments -- “chiasmata” During Metaphase 1, bivalents are aligned at equator not individual chromosomes Meiosis and Gametes

23. During Meiosis I parental homologous chromosomes are independently sorted to daughter cells Chromosome reduction occurs during Meiosis I Interkinesis What happens during Meiosis II? Chromosome reduction ---- sister chromatids separate Gametes produced McGraw-Hill sorting Meiosis and Gametes

24. Comparison of Meiosis and Mitosis Metaphase looks different for each process 2N=4 Meiosis and Gametes

25. Homework assignment: 10 points: due next class For a cell where 2N=6, draw a series of diagrams showing the chromosomes moving through the stages of meiosis. In one of the diagram clearly label: -- a pair of homologous chromosomes -- a bivalent Label all stages Make diagrams large, clear and neat Also answer the following questions: For an organism with a chromosome number of 2n = 56: A. How many pairs of homologous chromosomes does each normal body cell possess? ___ B. How many chromosomes does each cell possess after mitosis? ____ C. How many pairs of sister chromatids are present at the beginning of meiosis? ___ D. How many bivalents will form during prophase-I? ____ E. How many chromosomes does each cell possess after meiosis? ___ Drawings must be neatly done and chromosomes drawn with adequate detail. Chromosomes, bivalents and spindle fibers must be recognizable as these structures. Meiosis and Gametes

26. Why does meiosis in females yield only 1 viable gamete? Why does spermatogenesis in males assure 50:50 ratio of males to females? Sex of the sperm determines sex of the offspring Meiosis and Gametes

27. How can errors during meiosis cause Congenital birth disorders? Non-disjunction of chromosomes e.g., Down’s syndrome “trisomy 21” -- an example of “aneuploidy” Many effects -- reduced intellectual development -- heart and kidney defects -- often fatal -- early onset Alzheimer's Meiosis and Gametes

28. How does meiosis create genetic diversity? 1) crossing over 2) random assortment of chromosomes and later … 3) random pairing of gametes Meiosis and Gametes