Transcript Slide 1
Mitosis and the Cell Cycle Big Idea: Mitosis is the process in which the nucleus divides to form two new nuclei and two cells with identical DNA. 1 1 How do little elephants grow up to be BIG elephants? Mitosis begins after fertilization 1 cell becomes 2 cells, becomes 4 cells…becomes TRILLIONS Why do cells make more cells? Somatic Cells – body cells › Produced through mitosis › Has 46 chromosomes (23 pairs) Homolog – each member of a chromosome pair Diploid (2n) – total of 46 chromosomes in people – zygote & somatic cells Haploid (n) – total of 23 chromosomes in people, gametes (sperm & egg) Animated Mitosis Cycle http://www.cellsalive.com/mitosis.htm • Interphase • Prophase • Metaphase • Anaphase • Telophase & Cytokinesis Chromosomes are copied (# doubles) • Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase • Nucleus CELL MEMBRANE Cytoplasm Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm Growth Stage 1 (G1) – metabolic activity of the cell Synthesis Stage (S) – metabolic activity of the cell, replication of DNA Growth Stage 2 (G2) – metabolic activity of the cell, prepare for division • • • • Mitosis begins (cell begins to divide). Centrioles (or poles) appear and begin to move to opposite ends of the cell. Nuclear Envelope disappears. Spindle fibers form between the poles. Centrioles Sister chromatids Spindle fibers Animal Cell Plant Cell Spindle fibers Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm Chromatids (or pairs of chromosomes) attach to the spindle fibers at the centromere. • Chromosomes move to the equator of the cell. • Centrioles Spindle fibers Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm • • Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Centromere is broken in half. Centrioles Spindle fibers Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm Two new identical nuclei form (nuclear envelopes reform). • Chromosomes uncoil and appear as chromatin (threads rather than rods). • Mitosis ends. • Nuclei Chromatin Nuclei Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm • Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes. Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase Interphase Prophase Metaphase Anaphase Telophase Cytokinesis IPMATC I Prefer Meatloaf At Tennis Camp 23 - Cell Division 24 24 http://www.cellsalive.com/mitosis.htm