1. Cell Division (chapter 9) Cancer (chapter 17)

2. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. MITOSIS (Somatic Cell Division)

3. The Cell Cycle **Orderly set of steps of eukaryotic cell divisions (Remember: prokaryotes divide via binary fission) Why do Cells Divide? Growth (S.A. to volume ratio) Reproduction (in single celled organisms) Repair(S.A. to volume ratio)

4. a. ________________ b. ________________ c. _________________ d. _________________ e. _________________ f. __________________ f.

5. Interphase Prophase Prometaphase Metaphase Anaphase Telophase (cytokinesis) IPPMATc

6. Interphase  M-phase ( Mitosis) & Cytokinesis Interphase – resting and regenerating phase Mitosis – Nuclear division that results in identical complete copies of chromosomes packaged into two new nuclei Cytokinesis – Cytoplasmic division that results in two daughter cells

7. Chromosome Organization DNA is wrapped around proteins (histones), forming beadlike units called nucleosomes. A eukaryotic chromosome contains strings of nucleosomes called chromatin. At mitosis, the replicated chromatids are held together at the centromere. During mitosis, sister chromatids, attached by cohesin protein, line up at the equatorial plate, and attach to the spindle. *Telomeres are protective caps on ends; made of “junk” DNA code (TTAGGG – repeated)

10. Karyotype

11. Chromosome # = Organism Size

13. Interphase (G1, S, G2): Resting, Synthesizing, Preparing Prophase: Chromosomes visible, nuclear envelope breaks down, spindle forms as centrioles move to poles Metaphase: Chromosomes line up along equatorial plane Anaphase: Chromatids separate and move to poles Telophase: Prophase reversed, cytokinesis begins

14. **In plant cells, cytokinesis begins when a new cell wall forms between the two new cells. **In animal cells, the two new cells pinch and pull apart

15. Mitosis produces 2 daughter cells: The two daughter cells contain the exact same number of chromosomes as the original parent cell Daughter cells are DIPLOID (2n)

17. Control of the Cell Cycle G1 Checkpoint - Check to see if DNA is damaged G2 Checkpoint - Check to see if DNA is replicated properly M Checkpoint - spindle assembly checkpoint, check for alignment of chromosomes Apoptosis - programmed cell death, if any of the checks fail Cyclins & CDK (cyclin-dependent kinase) regulates the Cell Cycle

18. 1.Name the phases starting at the top.

19. 2. Name the phase 3. Identify X 4. Identify Y

20. 5. Name the phase

21. 6. Name the phase

22. 7. In humans, each cell (except sex cells) has how many chromosomes? ______ 8. After mitosis, how many daughter cells are produced? _______ 9. After mitosis (in a human cell), each daughter cell has how many chromosomes? ____ 10. How many phases are in MITOSIS? ___________ 11. Which phase of the cell cycle is the longest? _________ 12. During which phase does cytokinesis begin? _________ _

23. The Cell Cycle and Cancer Cancer: cellular growth disorder that results from the mutation of genes that regulate the cell cycle (neoplasm: abnormal growth of cells) benign: non-cancerous malignant: cancerous Cancer cells lack differentiation have abnormal nuclei form tumors undergo metastasis (spreading of malignant cells to adjacent tissues) & angiogenesis (providing a blood supply)

24. Causes of Cancer Viruses (some) Mutations (most = ~85%) –In somatic cells Spontaneously caused Carcinogenically caused –UV, chemicals, toxins, asbestos, smoke, etc.

25. Oncogenes (cancer genes)

26. Tumor Suppressor Genes

27. Two-Hit Hypothesis

28. HeLa Cells A HeLa cell (also Hela or hela cell) is a cell type in an immortal cell line used in scientific research. It is the oldest and most commonly used human cell line. The line was derived from cervical cancer cells taken from Henrietta Lacks, a patient who eventually died of her cancer on October 4, 1951. Article on Henrietta Lacks

29. Meiosis (Germ Cell Division) Provides for genetically unique offspring Also called reduction division Each diploid (2n) parent cell in the reproductive organ will create 4 haploid (n) daughter cells Haploid cell (n) + haploid cell (n) = diploid (2n) zygote Interphase  Meiosis I (cytokinesis)  Meiosis II (cytokinesis)

30. Interphase: G1,S, G2 Meiosis I: PPMATc –PI - Synapsis (crossing over of homologues) –AI – Independent assortment *Chromatids stay in pairs Meiosis II: PPMATc –Identical to Mitotic phases

31. Meiosis I

32. Crossing Over

33. Meiosis II

35. Prophase I may last a long time… Human males: about 1 week for prophase I and 1 month for entire meiotic cycle. Human females: prophase I begins before birth, and ends up to decades later during the monthly ovarian cycle.

37. There can be mutations resulting in aneuploidy (monosomy, trisomy)