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Control of cell replacement

Density-dependent inhibition Low amounts of growth factor proteins Growth Factor Secreted by cells stimulating division Enough cells, reaches GF saturation, inhibition. Control of cell replacement. Cancer - Disease of the cell cycle. Excessive division (out of control); tumor

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Control of cell replacement

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  1. Density-dependent inhibition Low amounts of growth factor proteins Growth Factor Secreted by cells stimulating division Enough cells, reaches GF saturation, inhibition Control of cell replacement

  2. Cancer - Disease of the cell cycle • Excessive division (out of control); tumor • Benign; removed if pushing against vital organs • Malignant; disrupts normal tissue & organ function • Metastasis; spreads to other tissues via bloodstream & lymph

  3. Carcinoma Epithelial cells (e.g. skin, intestinal lining) Sarcoma Connective or supportive tissue (e.g. bone, cartilage, muscles, fat, blood vessels) Leukemia Blood or bone marrow; specifically WBC’s Lymphoma Originates in lymphocytes (immune cells)

  4. Somatic cells (typical body cell) have 46 chromosomes, or 23 matched pairs Homologous chromosomes or homologues Both have genes that code for the same characteristics Will be at the same location or locus e.g. if we think chromosomes as sets of instructions or manuals, we have two versions, and loci would be chapters Chromosomes, sex cells, and meiosis

  5. We inherit one from each parent of the 23 pairs in humans 22 pairs are autosomes 1 pair are sex chromosomes XX females XY males Why do we have two versions?

  6. If we have two sets, than how do our gametes only have one set? • Tetrad = homologues come together, synapsis, (each with sister chromatids) • Crossing over = mixing or exchange of genes between homologues

  7. Note: no Interphase • No duplication of chromosomes

  8. Fertilization of sperm and egg produces variety of offspring • 3 places for variation • Tetrad formation and crossing over • Prophase I • Independent assortment • Depends on orientation of chromosomes during Metaphase I & II • Random fertilization • Preferably outside of family

  9. Sites of crossing over = chiasma Prophase I

  10. Karyotype = inventory of chromosomes in mitotic metaphase

  11. Karyotyping process • centrifuge? • Purpose / result of hypotonic solution?

  12. Digital arrangement of chromosomes by size & shape Stained and compared

  13. Trisomy 21 Down Syndrome Cause? Nondisjunction chromosome pair does not seperate Meiotic abnormalities

  14. Nondisjunction can also affect sex chromosomes • XXY: male with some female characteristics and underdeveloped sterile testes • XO: female, typically sterile, shorter, decreased development (treated with estrogen supplements)

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