0801 tumors
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0801 tumors



IBSL/IBHL Biology tumors notes, chapter/topic 2.5

IBSL/IBHL Biology tumors notes, chapter/topic 2.5



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    0801 tumors 0801 tumors Presentation Transcript

    • 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
    • Normal and Breast Cancer Mammogram
    • Some cancer cells have the ability to travel or “metastasize”
    • primary and secondary cancers
    • Control of the Cell Cycle
      • cell cycle proceeds on it’s own clock, but is regulated at certain checkpoints
    • 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
    • How do cells know when to stop dividing? contact inhibition
      • cancerous cells have lost this inhibition
    • 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
    • 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