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.