Cell Growth & Division

10.1 -

 10.2 - Mitosis
Mitosis is a process in which the cell prepares to divide by separating its chromosomes evenly, so that each daughter cell will receive one copy of each chromosome.

There are four stages of Mitosis:
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase

For more information, please refer to the attached PowerPoint presentation on Mitosis.

 10.3 - Regulation
Regulation of the cell cycle is important in order to make sure that cells are produced at an appropriate rate - not too many, nor too few.  Some factors that regulate the cell cycle include...
  - proteins within the cell
  - signals from other cells/organs
  - environmental signals (such as nutrient availability)

There are three main "checkpoints" in the cell cycle where the progress of the cell in its cycle is monitored.
  1. The G1 Checkpoint
     - Checks if conditions are good and whether the cell is healthy
        and large enough to divide.
     - If all is well, the cell proceeds to the Synthesis phase.
     - If not, the cell enters a "resting" phase until conditions improve.
  2. The G2
Checkpoint
     - Checks for mistakes in the copied DNA & makes corrections.
     - Also checks whether the cell is large enough to divide.
     - If requirements are met, the cell proceeds to Mitosis.
  3. The Mitosis Checkpoint
     - During metaphase, while the chromosomes are lined up,
        checks that the chromosomes are attached to the spindle
        fibers properly, so that both daughter cells will receive the
        same DNA.

Cancer is a set of diseases caused by the uncontrolled growth and division of abnormal cells.  This is triggered by damage to the DNA.  The defective cells reproduce again and again to form a tumor (a mass of defective cells).  Tumors can be...
  - benign - The tumor doesn't spread and can be removed by
     surgery.
  - malignant - The tumor invades and destroys healthy tissue.
The process whereby malignant cells break loose from a tumor and spread through the body is called metastasis.  (We would say that the cancer has metastasized.)  Treatments for cancer include...
  - chemotherapy - The use of cancer-killing drugs.
  - radiation therapy - The use of high-energy rays to kill cancer cells
  - surgery - Physically removing the tumor.

Subpages (1): Files for Cell Growth