Cell Cycle The cell cycle describes the cells
Cell Cycle • The cell cycle describes the cell’s activities in the state of • non-division (interphase) • and division (mitosis). (cells can only come from cells)
Interphase • Cell builds up store of energy • Organelles are duplicated • DNA replicates just before mitosis starts (individual chromosomes not visible)
The four phases of mitosis are • • prophase metaphase anaphase telophase
Prophase • The chromosomes become visible. (short, thick and duplicated). • Centrioles move to opposite poles. • Spindle fibres start to form. • Nuclear membrane dissolves.
Middle Metaphase • Chromosomes line up along the equator • Chromosomes connected – from centromere – to both centrioles – by the spindle fibres
Apart Anaphase • Centromere splits • Spindle fibres contract • Chromosomes separate and are pulled to opposite poles
Two Telophase • Nuclear membrane re-forms around each set of chromosomes • Chromosomes no longer visible now called chromatin. • Spindle dissolves.
Cytokinesis • Division of cytoplasm • Cleavage furrow formation in animal cells • Cell plate formation in plant cells.
• In Unicellular Organisms =Reproduction • In Multicellular Organisms =Growth • Produces new cells, not new individuals • Responsible for growth & renewal and repair of cells
Mitosis • Type of cell division • 2 identical daughter cells produced • No change in chromosome number • Occurs in somatic (body) cells • No variation
Cancer • Uncontrolled cell division -cells divide too fast and too often • No control of mitosis • Cells don’t stop dividing when they should • (usually when in contact with other cells) • Caused by – uv radiation, cigarette smoke
Arrange in correct order
Do I know…. • • • the stage when the cell is not dividing the 4 stages of mitosis the events of prophase the events of metaphase the events of anaphase the events of telophase
Do I know…. • how the cytoplasm divides in animal cells • how the cytoplasm divides in plant cells • the function of mitosis in single celled organisms • the functions of mitosis in multi-celled organisms
Next haploid/diploid meiosis (descrp & diffs and functions) chromosome • • • Contemporary Issues & Technology Tissue culture: Explanation: a technique in which individual cells are grown and divide in a bath of sterile nutritive fluid which often contains hormones and growth substances. Reference to any two applications: cancer research, plant breeding, routine analysis of chromosome karyotypes.
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