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“ALL CELLS COME FROM PRE-EXISTING CELLS”

“ALL CELLS COME FROM PRE-EXISTING CELLS”. Cell Division What are two different types of reproduction?. WHAT MUST TAKE PLACE FOR A CELL OR ORGANISM TO REPRODUCE?. Bacterial cell division (binary fission). Eukaryotic Cell Division (Mitosis) is much more complex.

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“ALL CELLS COME FROM PRE-EXISTING CELLS”

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  1. “ALL CELLS COME FROM PRE-EXISTING CELLS”

  2. Cell Division What are two different types of reproduction? WHAT MUST TAKE PLACE FOR A CELL OR ORGANISM TO REPRODUCE?

  3. Bacterial cell division (binary fission)

  4. Eukaryotic Cell Division (Mitosis) is much more complex What are some of the roles of mitosis in eukaryotes?

  5. The functions of Mitotic cell division: 1.) Reproduction Asexual reproduction of a unicellular, eukaryotic organism

  6. 2.) Development

  7. 3.) Tissue renewal in adults

  8. Figure 12.2 Eukaryotic chomosomes

  9. Figure 12.3 Chromosome duplication and distribution during mitosis

  10. Figure 12.0 Mitosis

  11. Figure 12.4 The cell cycle

  12. Figure 12.5 The stages of mitotic cell division in an animal cell: G2 phase; prophase; prometaphase

  13. Figure 12.5 The stages of mitotic cell division in an animal cell: metaphase; anaphase; telophase and cytokinesis. Pig cell mitosis

  14. Pig cell mitosis

  15. Figure 12.8 Cytokinesis in animal and plant cells

  16. “To divide or not to divide, that is the question”

  17. Anchorage Dependence and Density-dependent inhibition of cell division

  18. External Signaling: G1 checkpoint, Growth factors Ex. PDGF receptor cell cycle control

  19. BIOLOGY OF CANCER Cancer is the loss of normal cell cycle regulation (a cell starts dividing out of control) What can cause this? Genes that play a role in normal cell cycle control are altered in some way. 1. Genes that stimulate cell division Normal version of gene: Proto-oncogene Mutated version: Oncogene

  20. Mechanical analogy for the cell cycle control system

  21. 2. Tumor Suppressor Genes: Two Classes - Genes involved in blocking cell division (checkpoints) - DNA Repair Genes (fix mutations in DNA) Most common examples: Rb, retinoblastoma. Involved in childhood cancer (two defective copies are required for disease ), but also in adult tumors such as bladder, breast and lung carcinoma. The Rb protein is a key target for the oncogene products of many tumor viruses, including SV40, adenoviruses, and papillomaviruses. They all bind to Rb and inhibit its activity. P53 is mutated in 50% of all cancers. It’s a target of the same tumor viruses That target Rb. P53 is required for apoptosis induced by DNA damage APC: is mutated in hereditary colon cancer BRCA1 and 2: responsible for hereditary breast cancer

  22. To develop cancer it takes multiple mutations in the same cell. At least two mutations: One oncogene, one tumor suppressor gene. Some people are predisposed to getting a particular type of cancer. (Genetic Pre-dispositions)

  23. The growth and metastasis of a malignant breast tumor Terminology: Tumor (benign and malignant) Metastasis

  24. So what causes these mutations that can result in the development of Cancer??? Environmental Exposure: -Radiation -Viruses -Air (indoor and outdoor) and water pollution -Consumer products -Food -Cosmetics -Medicines -TIME!

  25. How do we cure cancer? Prevention Treatment old and new drugs Examples: endostatin and angiostatin retinoic acid to induce differentiation inhibitors of farnesylation (Ras oncogene) Herceptin (antibodies against erbB-2 gene) Inhibitor of specific protein tyrosine-kinases (Gleevec)

  26. REPRODUCTION “ASEXUAL OR SEXUAL, THAT IS THE QUESTION”

  27. Figure 13.1 The asexual reproduction of a hydra

  28. Figure 13.2 Two families

  29. The human life cycle

  30. Three sexual life cycles differing in the timing of meiosis and fertilization (syngamy) Alternation of generations

  31. Human female chromosomes shown by bright field G-banding

  32. Haploid chromosome # = n (humans: n =23) Homologous pair Eggs & sperm Diploid # =2n (humans: 2n = 46) All other cells (somatic)

  33. The human life cycle

  34. Overview of meiosis: how meiosis reduces chromosome number

  35. The stages of meiotic cell division: Meiosis I

  36. The stages of meiotic cell division: Meiosis II

  37. A comparison of mitosis and meiosis

  38. Figure 13.9 The results of alternative arrangements of two homologous chromosome pairs on the metaphase plate in meiosis I (Independent Assortment)

  39. For 2 homologous chromosomes: 4 possible gametes (22) For 23 homologous chromosomes: 223 = 8 million possible gametes! So, upon formation of a zygote, 8 mil. X 8 mil. = 64 trillion!

  40. Figure 13.10 The results of crossing over during meiosis

  41. Sources of genetic variability: 1. Independent assortment 2. Crossing over (recombination) 3. Random fertilization of ovum by sperm. 4. MUTATION - ultimate source of genetic variability

  42. ERRORS IN MEIOSIS

  43. Testing a fetus for genetic disorders

  44. The risk of nondisjunction increases dramatically with age. 30 yr. old mother: 1/1000 , 40 yr. old mother: 1/100

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