cell cycle consists of the following: –g1 phase –s phase –g2 phase –m phase –cytokinesis
TRANSCRIPT
Cell Cycle
• Consists of the following:
–G1 phase
–S phase
–G2 phase
–M Phase
–Cytokinesis
Interphase• G1 phase
–Cell grows in size.
–Normal cellular activities occur.
–8-10 hours
Interphase
• S phase–Chromosomes
replicate. (DNA replicates)
–6-9 hours
Interphase
• G2 phase–Enzymes are synthesized.
–Cell growth continues.
–4-6 hours
Early Prophase
• Chromatin fibers shorten and condense.
• Chromatids are held together by a centromere.
Late Prophase• Nucleolus disappears.• Spindle forms. The
spindle extends from pole to pole.
• Asters radiate from spindle.
• Centrioles hold the spindle at each pole.
• Nuclear membrane disappears.
Metaphase
• Chromatid pairs line up along the equator of the cell.
Anaphase
• Centromeres split which separate the chromatids.
• Chromosomes move to opposite poles of the cell.
Telophase• Begins after
chromosomal movement stops.
• Spindle breaks down.
• Nucleolus reappears.
• Nuclear membrane reappears.
Cytokinesis• Not a part of
mitosis.
• Division of the cytoplasm.
• Cleavage furrow can form in late anaphase or early telophase.
Cancer
• Cells in body divide out of control.
• Excess tissue forms a tumor.
• Cancerous tumor is called a malignant tumor.
Types of cancer
• Most human cancers are carcinomas (arise from epithelial cells).
• Melanomas are cancerous growths of melanocytes.
Types of cancer
• Sarcoma is a general term for any cancer arising from muscle cells or connective tissues.
Causes of cancer
• Cause: Environmental agents called a carcinogen. Carcinogens induce mutations- change in the DNA sequence.
• Cancer-causing genes called oncogenes.
Treatments
• Chemotherapy: Drugs that are administered that poison cancer cells.
• Radiation destroys the chromosomes of cancer cells.
• Surgery is used to remove the tumor.
• Both chemotherapy and radiation can disrupt the function of normal cells.