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The Cell Cycle

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

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The Cell Cycle

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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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