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Understanding the Cell Cycle: Mitosis and Cell Division

Learn about the stages of cell growth, mitosis, and cytokinesis in this informative guide. Explore keywords such as somatic cells, gametes, chromosomes, diploid, haploid, chromatin, chromatids, and centromere.

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Understanding the Cell Cycle: Mitosis and Cell Division

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  1. The Cell Cycle http://www.nclark.net/MitosisRap.mp3

  2. Cell Division: Key Terms • Somatic cells (body cells) • Gametes (reproductive cells): sperm and egg cells • Genome: cell’s genetic information • Chromosomes: DNA molecules • Diploid (2n): 2 sets of chromosomes • Haploid (1n): 1 set of chromosomes • Chromatin: DNA-protein complex • Chromatids: replicated strands of a chromosome • Centromere: narrowing “waist” of sister chromatids

  3. General info. • ~ 10 trillion cells in body all from one cell by mitosis. • Erythrocytes (RBC) made one million per second • Cell division (mitosis) • Single celled = more individuals • Multi-celled = growth, differentiation and repair. • 2 basic function • Duplicate the cell • Ensure daughter cell has complete copy DNA • The basic steps are • Duplicate the DNA • Divide the chromosomes into two complete sets • Divide the cell into two daughter cells • Same for Prokaryotes and Eukaryotes http://highered.mcgraw-hill.com/sites/0073031216/student_view0/exercise13/mitosis_movie.html http://www.nationalgeographic.com/adventure/video/index.html

  4. The Cell Cycle • Cell Life Cycle. • Stages of Cell Growth • Interphase (90% of cycle) • G1 phase: primary growth phase. Cell does its 'job'. • S phase: DNA replication • G2 phase: Chromosome condensation, cell organelle replication • Mitotic phase • M phase: mitosis (nuclear division) • C phase: cytokinesis (cytoplasmic division) • daughter cells form http://www.sinauer.com/cooper/4e/animations1601.html http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter11/animations.html#

  5. Mitosis • Prophase • Prometaphase • Metaphase • Anaphase • Telophase http://www.johnkyrk.com/mitosis.html http://www.sumanasinc.com/webcontent/animations/content/mitosis.html

  6. Prophase • Pairs of Chromosomes (sister chromatids) visible • Nucleoli disappear • Mitotic spindle forms • Centrosomes (centrioles) move

  7. Prometaphase • Nuclear membrane fragments • Spindle fibers interaction with chromosomes • Kinetochore develops

  8. Metaphase • Chromatid pairs meet in the Middle of the cell • Centrosomes at opposite poles • Kinetochores of sister chromatids attached to microtubules (spindle)

  9. Anaphase • Sister chromatids come Apart • Chromosomes move to opposite poles • Each pole now has a complete set of chromosomes

  10. Telophase • Cytokinesis occurs forming Two new cells • Daughter nuclei form • Nuclear envelopes arise • Chromatin becomes less coiled • Two new nuclei complete mitosis http://www.loci.wisc.edu/outreach/bioclips/CDBio.html

  11. Cytokinesis • Cytoplasmic division • Animals: cleavage furrow • Plants: cell plate http://biology.nebrwesleyan.edu/benham/mitosis/

  12. http://www.nobelprize.org/educational/medicine/2001/cellcycle.htmlhttp://www.nobelprize.org/educational/medicine/2001/cellcycle.html Cell Cycle regulation • Growth factors • Cyclins control the cell cycle , causing movement from G1 to S or G2 to M • Cdk (cyclin dependent kinase) work with cyclins • MPF (Maturation Promoting Factor) includes CdK and cyclins • p53 blocks cell cycle if DNA is damaged. • Density-dependent inhibition • crowded cells stop dividing • Anchorage dependence • to divide cells must be attached to a substrate or tissue matrix http://www.sinauer.com/cooper/4e/animations1604.html

  13. Cancer • Uncontrolled, rapid cell division • Cancer cells: • ignore cell cycle regulation signals • break away and settle in other parts of the body (metastasis) • don’t maintain function • consume lots of resources • Mutagens that change genes cause cancer (Carcinogens) • Oncogenes turn on cell division normally silent if moved they become active • Cancer cells are believed to be immortal. • Tumor: benign (harmless) or malignant (harmful) http://www.metacafe.com/watch/1872431/3d_medical_animation_what_is_cancer/ http://www.hhmi.org/biointeractive/media/angiogenesis-lg.mov

  14. http://www.pbs.org/wgbh/nova/sciencenow/3209/04.html Differentiation • Specialization and division of labor. • Pre-differentiation are stem cells • Totipotency: ability of a cell to divide and produce all the differentiated cells in an organism • Each cell has all the instructions (DNA) to produce a whole human • Nearby cells and/or the external environment triggers differentiation • Ensures efficiency in multicellular organisms • Groups of cells differentiate to form tissues and organs http://www.cnn.com/SPECIALS/2001/stemcell/

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