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IBSL/IBHL Biology tumors notes, chapter/topic 2.5

IBSL/IBHL Biology tumors notes, chapter/topic 2.5

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  • 1. Tumor Formation
    • Sometimes the normal control of mitosis in a cell fails
    • This cell divides into two
    • The two daughter cells divide to form four cells
    • Repeated divisions soon produce a mass of cells called tumor
    • This can happen in any organ
    • Tumors can grow to a large size and can spread to other parts of the body
    • The diseases caused by the growth of tumors are called cancer
  • 2. Normal and Breast Cancer Mammogram
  • 3. Some cancer cells have the ability to travel or “metastasize”
  • 4. primary and secondary cancers
  • 5. Control of the Cell Cycle
    • cell cycle proceeds on it’s own clock, but is regulated at certain checkpoints
  • 6. breast cancer cell
    • cells can become cancerous for several reasons:
    • - damage to DNA
    • - environmental exposure toxins; examples: *PCB’s--polychlorinated biphenyl *DDT--dichlor-diphenyl- trichlorethylene
    • - other cell control issues
    • - damaged proteins
    • - genetic factors
  • 7. How do cells know when to stop dividing? contact inhibition
    • cancerous cells have lost this inhibition
  • 8. Features of cancer cells cell shape is easily distinguished from normal, healthy cells cancerous cells lose their attachment to neighboring cells cancer cells may have an unusual # of chromosomes cancer cells can go on dividing indefinitely , if they have an unlimited supply of nutrients they are said to be “immortal” metabolism may be drastically altered and the cell stops functioning in a constructive way
  • 9. Oncogenesis, proto-oncogenes and tumor suppressor genes There are two types of genes necessary for normal control of cell division: 1. proto-oncogenes (start cell division and are essential for normal cell development) 2. tumor suppressor genes (switch off cell division) Oncogenes: these arise when these cell cycle control genes become mutated -- these mutations lead to uncontrolled cell division Ex: many cancers are initiated when there are mutations in tumor-suppressor genes p53 : this tumor suppressor gene encodes for a protein that halts the cell cycle so that DNA can be repaired before division