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Spring 2010 chapter 3c PowerPoint for BIOL2401 (Human Anatomy & Physiology) at San Antonio College with Alba

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  1. 1. The Cytoskeleton <ul><li>A networked mesh of protein rods that support the cell, acting as scaffolding </li></ul><ul><li>Also contain contractile units that allow for the movement of cells and for intracellular movement (organelle movement, vesicular transport) </li></ul><ul><li>Three Types: </li></ul><ul><ul><li>Microtubules </li></ul></ul><ul><ul><li>Microfilaments </li></ul></ul><ul><ul><li>Intermediate filaments </li></ul></ul>
  2. 2. Microfilaments <ul><li>Thin (but dense), cross-linked strands of actin (contractile proteins) </li></ul><ul><li>Involved in cell motility and changes in shape </li></ul>
  3. 3. Intermediate Filaments <ul><li>Tough, stable, permanent, rope-like protein fibers </li></ul><ul><li>Have high tensile strength </li></ul><ul><li>Helps cells resist mechanical stress and are found in desmosomes for cell-cell contact </li></ul>
  4. 4. Microtubules <ul><li>Long, hollow tubes composed of tubulin. Large in diameter </li></ul><ul><li>Radiate from the centrosome </li></ul><ul><li>Determine cell shape and organelle distribution </li></ul><ul><li>Important in intracellular transport </li></ul>
  5. 5. Centrosome & Centrioles <ul><li>“ microtubule organizing center” </li></ul><ul><li>Composed of two centrioles (90 o to each other) and a granular matrix </li></ul><ul><li>Matrix generates microtubules </li></ul><ul><li>Centrioles generate spindle fibers during cell division </li></ul>
  6. 6. Cellular Extensions: Cilia
  7. 7. Cellular Extensions: Flagella <ul><li>Sperm cells are the only cells in the human body with flagella </li></ul><ul><li>Similar to cilia but are longer and allow cells to propel themselves </li></ul><ul><li>Use a whip-like motion for locomotion </li></ul>
  8. 8. Cellular Extensions: Microvilli <ul><li>Finger-like plasma membrane projections </li></ul><ul><li>Increases plasma membrane surface area </li></ul><ul><li>Typically found in absorptive cells </li></ul><ul><li>Example: Lining of the small intestine </li></ul>
  9. 9. The Nucleus <ul><li>The “control center” of the cell containing genetic information </li></ul><ul><li>The largest organelle of the cell and is filled with nucleoplasm </li></ul><ul><li>Composed of: Nuclear envelope, Nucleolus, and Chromatin </li></ul>
  10. 10. The Nuclear Envelope <ul><li>Double membrane barrier separated by a fluid-filled space </li></ul><ul><li>Outer membrane is continuous with RER & is studded with ribosomes </li></ul><ul><li>Inner membrane is lined with nuclear lamina </li></ul><ul><li>Two membranes come together and form nuclear pores (entry and exit point of particles) </li></ul>
  11. 11. Nucleoli <ul><li>Small, dense body composed of RNA and protein, where ribosomes are synthesized </li></ul>
  12. 12. Chromatin <ul><li>Loosely coiled DNA fibers and histone proteins, condense to form chromosomes. </li></ul><ul><li>DNA + histone = nucleosome </li></ul><ul><li>Condense into chromosomes during cell division </li></ul>
  13. 13. The Cell Cycle <ul><li>Cell cycles form a multi-celled organism from one original cell </li></ul><ul><li>A series of changes cells go through from the time they are formed until they divide </li></ul><ul><li>Promote growth and tissue repair in organisms </li></ul><ul><li>Involves phases and checkpoints for quality control </li></ul>*Movie time!
  14. 14. Interphase <ul><li>Cell growth and DNA replication, “preparation period” </li></ul><ul><li>G1 Phase: Growth Phase 1, structures are duplicated </li></ul><ul><li>S Phase: Synthesis Phase, DNA is replicated </li></ul><ul><li>G2 Phase: Growth Phase 2, more structural duplication, final preparations </li></ul>
  15. 15. DNA Replication <ul><li>Occurs before cell division </li></ul><ul><li>DNA is uncoiled & H-bonds broken by a helicase </li></ul><ul><li>DNA polymerase introduces complementary bases </li></ul><ul><li>Replicated DNA is semi-conservative </li></ul><ul><li>DNA condenses after replication </li></ul>
  16. 16. Mitosis <ul><li>Division of the nucleus: </li></ul><ul><ul><li>Prophase </li></ul></ul><ul><ul><li>Metaphase </li></ul></ul><ul><ul><li>Anaphase </li></ul></ul><ul><ul><li>Telophase </li></ul></ul><ul><li>Cytokinesis: Division of the cytoplasm </li></ul><ul><li>Exceptions: RBCs, nervous, skeletal & cardiac tissue </li></ul>
  17. 17. Mitosis
  18. 18. Mitosis
  19. 19. Protein Synthesis <ul><li>DNA provides the information for protein synthesis </li></ul><ul><li>Two events: </li></ul><ul><ul><li>Transcription </li></ul></ul><ul><ul><li>Translation </li></ul></ul>
  20. 20. Transcription <ul><li>Synthesis of complementary mRNA (messenger RNA) </li></ul><ul><li>Transcribes the code for making proteins and transports it outside the nucleus </li></ul>
  21. 21. Translation
  22. 22. Translation <ul><li>Every mRNA codon corresponds to an amino acid </li></ul><ul><li>Examples: </li></ul><ul><ul><li>CAC = Histidine </li></ul></ul><ul><ul><li>CAA = Glutamine </li></ul></ul><ul><ul><li>AAA = Lysine </li></ul></ul>