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.

Metaphase Chromosomes line up along the equator Chromosomes connected Middle Chromosomes line up along the equator Chromosomes connected from centromere to both centrioles by the spindle fibres

Anaphase Centromere splits Spindle fibres contract Apart Centromere splits Spindle fibres contract Chromosomes separate and are pulled to opposite poles

Telophase Nuclear membrane re-forms around each set of chromosomes Two 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.