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Cell Growth and Division

Explore the reasons behind cell size constraints and the intricate processes involved in cell division. Learn about the importance of surface area, volume, DNA replication, mitosis stages, and cellular responses to injury. Discover how cyclins regulate the cell cycle and the implications of cancer on cellular health.

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Cell Growth and Division

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  1. Cell Growth and Division Chapter 10

  2. Why are cells so small? • DNA • Messages from the nucleus must be able to reach all parts of the cell • Diffusion • Nutrients must enter and wastes must leave • If the cell was too big, diffusion would happen too slowly

  3. Why are cells so small? • Surface Area vs. Volume • As a cell grows larger, the volume increases faster than the SA • A bigger cell needs more nutrients, but has relatively less SA to take in those nutrients

  4. Surface Area vs. Volume

  5. Cell Cycle • Cells divide before growing too large • Before dividing, cells must prepare • Preparation = Interphase • G1 phase: Cell grows larger • S phase: Cell makes new DNA for daughter cell • G2 phase: Cell makes new organelles for daughter cell

  6. Cell Cycle

  7. Centromere Sister Chromatids Chromosomes • Each chromosome is replicated during the S phase • A replicated chromosome has two identical sister chromatids connected by a centromere

  8. Mitosis

  9. Mitosis • Four Stages: • Prophase (pro- means first) • Metaphase (meta- means middle/after) • Anaphase (ana- means apart) • Telophase (telo- means far away/end)

  10. Chromosomes condensing Prophase • Chromatin condenses into chromosomes • Nuclear envelope and nucleolus disintegrate • Centrioles migrate to opposite ends of the cell • Spindle fibers form in foot ball shape across cell

  11. Prophase

  12. Metaphase • Chromosomes line up in the middle (equator) of the cell • Spindle fibers attach to centromeres

  13. Metaphase

  14. Anaphase • Sister chromatids separate • Spindle fibers shorten, pulling chromatids to opposite ends of cell • Animal cells begin to pinch in • Plant cells begin to form cell plate in the middle

  15. Anaphase

  16. Telophase • Nuclear membrane built from ER around each set of chromosomes • Nucleolus reforms in each nucleus • Chromosomes become mass of chromatin

  17. Telophase Two cells dividing into four

  18. Cytokinesis • Final division of cytoplasm resulting in two daughter cells • Animals – CM pinches together • Plants – Cell plate forms new CM dividing the daughter cells

  19. Plant Cell Division

  20. Anaphase Prophase Metaphase Telophase Interphase Which phases can you see?

  21. Knowing when to divide • Cyclins • Protein that regulates the cell cycle in eukaryotes • Internal regulators – tell the cell when to enter mitosis • External regulators – control the rate of the cell cycle

  22. Cellular Response to Injury

  23. Effect of Cyclins Cytoplasm is injectedinto a second cell in G2 phase Cytoplasm isremoved fromcell in mitosis Second cell enters mitosis

  24. Cancer • Cancer results when cells do not respond to cell cycle regulators • Cells grow unregulated, forming a tumor • Tumor damages surrounding tissue

  25. Leukemia – Blood cancer

  26. Mammary (Breast) Cancer

  27. Skin Cancer

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