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Cell Cycle, Mitosis, and Meiosis

Cell Cycle, Mitosis, and Meiosis. Why do cells divide?. Most cells go through a series of changes in order to maintain homeostasis. Cells need to reproduce ( divide ) when their surface area can no longer supply the much larger volume with nutrients and get rid of wastes. Cell Division.

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Cell Cycle, Mitosis, and Meiosis

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  1. Cell Cycle, Mitosis, and Meiosis

  2. Why do cells divide? Most cells go through a series of changes in order to maintain homeostasis. Cells need to reproduce (divide) when their surface area can no longer supply the much larger volume withnutrients and get rid of wastes.

  3. Cell Division • The process by which a cell divides into two new daughter cells

  4. Chromosomes • Made of DNA (carries the cell’s genetic information) and proteins • Every organism has a specific number of chromosomes • Humans have 46

  5. Chromosomes • Only visible during cell division • Each chromosome is copied before cell division • Each chromosome is made of two identical “sister” chromatids • Each pair of chromatids is attached by a centromere

  6. The Cell Cycle • The series of events that cells go through as they grow and divide

  7. The Cell Cycle • Interphase – the period of growth in between cell divisions • Three phases of interphase • G1 • S • G2

  8. Interphase – G1 phase • Phase where cells do the most growing • Cells increase in size and make new proteins and organelles

  9. Interphase – S phase • Chromosomes are replicated (copied) • Synthesis (making) of DNA molecules occurs

  10. Interphase – G2 • Organelles and other molecules required for cell division are produced. • Once completed, the cell will enter mitosis

  11. Mitosis • The division of the cell nucleus • Divided into four phases (PMAT): • Prophase • Metaphase • Anaphase • Telophase

  12. Prophase • Chromosomes become visible • Nuclear envelope breaks down • Centrioles separate • Spindles form

  13. Metaphase • Chromosomes line up along the center of the cell

  14. Anaphase • Sister chromatids separate • Individual chromosomes are moved apart

  15. Telophase • Chromosomes gather at opposite ends of the cell • Two new nuclear envelopes form

  16. Cytokinesis • The cytoplasm pinches in two – two new daughter cells are formed • In plants a cell plate divides the cytoplasm before the cell wall forms

  17. Cancer Cells 1. Normal cells contain check points to regulate the cell cycle, & stop at appropriate check points. 2. Cancerous cells do not respond to check points and continue rapidly through the cell cycle. This results in masses of undefined cells called tumors. 3. Cancer cells do not mature; they become more immature.

  18. Binary Fission • The asexual reproduction of a bacterial cell

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