3.8 The Cell Cycle

The cell cycle has three stages (represented by the small middle ring in the picture below)
1. Interphase
  1. Occupies most of the cell cycle and is sometimes known as the resting phase because no division takes place
2. Nuclear Division
  1. When the nucleus divides either into two (mitosis) or four (meiosis)
3. Cytokinesis
  1. Follows nuclear division and is the process by which the cytoplasm divides to produce two new cells (mitosis) or four new cells (meiosis)
Cancer
1. Caused by a growth disorder in cells
  1. The result of damage to the genes that regulate mitosis and the cell cycle
    1. Leads to uncontrolled growth and division of cells
      1. As a consequence to this, a group of abnormal cells forms, this is a tumour and it constantly develops and expands in size
        A Tumour becomes cancerous if it becomes from BENIGN, to MALIGNANT
2. Benign Tumours - Grow more slowly, are more compact and are less likely to be life-threatening
3. Malignant Tumours - Grow rapidly, are less compact and are more likely to be life-threatening
Rate of Mitosis
1. Most cells divide by mitosis, either to increase the size of a tissue during development (growth) or to replace dead and worn out cells (repair)
  1. The Rate of mitosis can be affected by the environment of the cell and by growth factors
    1. It is also controlled by two types of gene
      1. A mutation in one of these genes = uncontrolled mitosis
        Mutated cell divide = tumour
Treatment on Cancer
1. Usually involves killing dividing cells by blocking a part of the cell cycle
  1. Cell cycle disrupted = cell division and cancer growth ceases
2. Drugs used to treat cancer (chemotherapy) usually disrupt the cell cycle by ...
  1. ... preventing DNA from replicating
  2. ... Inhibiting the metaphase stage of mitosis by interfering with spindle formation
  3. Drugs are more effective against rapidly dividing cells
    1. Cancer cells = fast rate of division = they are damaged to a greater degree than normal cells
3. Problems?
  1. These drug also effect normal cells
  2. The drugs are more effective against fast dividing cells, this means that normal cells such as hair-producing cells are vulnerable to damage
The graph (left) shows the effect of a chemotherapy drug that kills dividing cells. It was given to a cancer patient once every three weeks starting at 0. This graph plots the changes in the number of healthy cells and cancer cell sin a tissue over the treatment period of 12 weeks

Nächster

3.8 The Cell Cycle

Beschreibung

Zusammenfassung der Ressource

Medienanhänge

ähnlicher Inhalt

	Erstellt von Bee Brittain vor mehr als 8 Jahre