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Senanu's Bio class

Chapter 12 – Cell cycle and mitosis

OBJECTIVE: Describe how most cell divisions results in genetically identical daughter cells. OBJECTIVE: Understand the relationship between chromosomes and sister chromatids, and how the number of these vary through the cell cycle.

  1. Draw a large reproduction of the cell cycle (Fig 12.3). In each of G1, S, and G2 phases, draw a chromosome as it would appear in a cell. Use Fig 12.4 to help.

    Your textbook introduces homologous chromosomes in the next chapter (p 279). These are 2 chromosomes that are usually similar (though not identical), carry the same genes and in diploids (like humans), we have 1 homolog inherited from each parent. Sister chromatids are identical copies of one another.

  2. The division of genetic material in the nucleus is a process called ____________ that is immediately followed by _______________, the division of the cytoplasm.
  3. What is the function of mitosis?
  4. What is a chromosome?
  5. What is a sister chromatid?
  6. How many chromosomes are in each human somatic cell?
  7. How many pairs of chromosomes are in each human somatic cell?
  8. Draw a cell with 2 pairs of chromosomes as the 4 chromosomes would look during G1 phase.
  9. Now redraw the cell to show how it would look after G2 phase.
  10. Summarize what happens in each of G1, S, and G2 phases of the cell cycle.
  11. List all the phases within M phase. You should be able to remember the order.
  12. Describe the main events of each phase. In particular, consider whether the nuclear envelope exists or not, what the spindle apparatus is doing, and, most importantly, where the chromosomes are located during each phase.
  13. Describe HOW the chromosomes move during Anaphase? Be sure to include what cellular structures are moving the chromosomes.
  14. Describe cytokinesis. What cell structures are involved?

  15. How does cytokinesis differ between plant and animal cells?

    OBJECTIVE: Describe the role of MPF in regulating the cell cycle

  16. What are the components of MPF? Which varies in its concentration and which is constant in the cell?

  17. Describe the role of MPF in controlling the onset of Mitosis.

    OBJECTIVE: Understand that the cell cycle is controlled by molecular interactions and the consequences of failed checkpoints (aka cancer).

  18. Describe the role of checkpoints for controlling the cell cycle. What happens if checkpoints don’t work?
  19. The following is a checklist of checkpoints showing the requirements before the cell cycle continues.
    1. G1 checkpoint checks for:
      1. size
      2. availability of nutrients
      3. social signals
      4. Damage to DNA (p53 is a tumor suppressor that checks for DNA damage)
    2. G2 checkpoint for:
      1. Damaged or unreplicated DNA
        1. Cdk’s inhibitory phosphate is not removed, prevents entry into Mitosis
    3. M-phase (after metaphase):
      1. checks kinetochores are attached properly
    4. M-phase (after anaphase):
      1. cyclin degraded only after proper separation of chromosomes
  20. Describe the role of growth factors (such as PGDF) in the development of cancer.
  21. Describe the role of the breakdown of density dependent inhibition and anchorage dependence in the development of cancer.
  22. what is the difference between benign and malignant tumors?