Cell Division
Are you two twins? Asexual Reproduction: Used by many unicellular organisms, plants, and lower animals. Involves only mitotic cell division = each offspring has exactly the same heredity as its parent. Usually rapid compared to sexual reproduction.
Phases of the Cell Cycle The cell cycle consists of Interphase (cell growth and copying of chromosomes in preparation for cell division) Mitotic (M) phase (mitosis and cytokinesis) Interphase (about 90% of the cell cycle) can be divided into subphases: G1 phase (“first gap”) – cell growth & normal functions S phase (“synthesis”) – DNA copies G2 phase (“second gap”) – mitosis
Animated Cycle http://www.cellsalive.com/cell_cycle.htm
Mitosis Cells divide to form 2 identical “daughter cells” Occurs in stages I PMAT C
Interphase The cell prepares for division DNA replicated Organelles replicated Cell increases in size
Interphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Mitosis Stage 1 - Prophase DNA coils into chromosomes Centrioles move to opposite sides of cell Nuclear membrane dissolves Spindle fibers form between the centrioles as they move apart
Prophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Mitosis Stage 2 - Metaphase Chromosomes attach to spindle fibers and line up in the middle
Metaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Mitosis Stage 3 - Anaphase Chromosomes separate Spindle fibers retract, pulling the chromosome pairs apart
Anaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Mitosis Stage 4 - Telophase New nuclear membrane forms around chromosomes Cell membrane pinches in to form the 2 new daughter cells
Telophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Mitosis Stage 5 - Cytokinesis Division of cytoplasm & organelles Begins in anaphase “Pinches off” between new nuclei to form 2 individual cells
Mitosis Cell division regulated by cell type (depends on gene activation) Uncontrolled cell division = cancer
Mitosis Animation http://www.cellsalive.com/mitosis.htm