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How do little elephants grow up to be BIG elephants?. Why do animals shed their skin?. Why Divide?. Growth Repair damaged cells Replace old cells. Skin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun.
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Why Divide? Growth Repair damaged cells Replace old cells Skin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun. Cell that reproduce by asexual reproduction reproduce constantly.
Stages of Cell Cycle http://www.cellsalive.com/mitosis.htm • Interphase • Mitosis • Prophase • Metaphase • Anaphase • Telophase • * Cytokinesis
Interphaseoccurs before mitosis begins • Chromosomes are copied (# doubles) • At the start, Chromosomes appear as threadlike coils called chromatin at the start, • After copying is done, each chromatin end up with an exact duplicate and they are called sister chromatids. CELL MEMBRANE Nucleus Cytoplasm
Interphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Prophase 1st step in Mitosis • Mitosis begins (cell begins to divide) • Chromosome condenses and now visible. • Centrioles(or poles) appear and begin to move to opposite end of the cell. • Spindle fibers form between the poles. Centrioles Sister chromatids Spindle fibers
Prophase Plant Cell Animal Cell Spindle fibers Centrioles Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Metaphase 2nd step in Mitosis • Chromosome line up at the middle. • Chromosomeattach to the spindle fibers. Centrioles Spindle fibers
Metaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Anaphase 3rdstep in Mitosis • Sister Chromatids separate and begin to move to opposite ends of the cell. Centrioles Spindle fibers
Anaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Telophase4th step in Mitosis • Nuclear membrane forms around chromosome • Chromosome uncoils and no longer visible. • Cell begins to pinch in the middle. Nuclei Nuclei Chromatin
Telophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Cytokinesisoccurs after mitosis • Organelles divide to each end • Cell membrane forms between the two sections of the cell and seperates. • Two daughter cells are formed– each with its own nucleus with identical chromosomes.
MitosisAnimation http://www.cellsalive.com/mitosis.htm