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Unit 4 VCE Biology: Cell membranes &_organelles

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Unit 4: Area of study 1: Biological macromolecules, cell membranes and organelles.

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Unit 4 VCE Biology: Cell membranes &_organelles

  1. 1. Unit 3 VCE Biology Cell membranes and organelles
  2. 2. Prokaryotic cell
  3. 3. Eukaryotic (animal) cell
  4. 4. Cell membrane – phospholipid bilayer
  5. 5. Cell membrane with embedded proteins
  6. 6. Two types of proteins in membranes: • Integral proteins that are embedded or inserted into the cell membrane. • Peripheral proteins that are attached to the surface of the cell membrane. • The functions of these proteins include transportation, enzymes, receptor sites, cell adhesion and attachment to the cytoskeleton.
  7. 7. Through the cell membrane • Diffusion (passive) • Osmosis (passive) • Facilitated diffusion (passive) • Active transport (requires energy) • Bulk transport (requires energy)
  8. 8. Diffusion • Passive movement of molecules from an area of high concentration to low concentration. • Concentration gradient is the difference in concentration between the two regions. • Small, uncharged molecules (CO2, H20 and O2) move easily through the membrane. • Works well over short distances, but slows once molecules enter the cell. • Limits cell size.
  9. 9. Diffusion (passive)
  10. 10. Osmosis • Osmosis is the process by which water moves through a semi-permeable membrane from an area of high concentration (of water) to lower concentrations. • It is a passive process and therefor does not require energy.
  11. 11. Osmosis – diffusion of water
  12. 12. Facilitated diffusion • Channel mediated - Some substances diffuse with the assistance of protein channels • Carrier mediated - Substances move down the concentration gradient via specific carrier molecules. Slower than channel-mediated as the protein carrier has to change shape for each molecule it transports.
  13. 13. Facilitated diffusion - passive
  14. 14. Active Transport • Movement of dissolved substances into or out of cells against a concentration gradient. • Active transport requires energy and involves a carrier protein for each substance that is actively transported. • Includes endocytosis (into cell) and exocytosis (out of cell). • Transport vesicles fuse with the membrane to consume or excrete substances.
  15. 15. Active Transport • Pinocytosis is when a liquid is consumed or excreted. • Phagocytosis is when a solid substance is consumed or excreted. • Cell walls lie outside the plasma membrane in plant, fungal and prokaryotic cells. • Endocytosis and exocytosis can occur into and out of the cell vacuole.
  16. 16. Active Transport – requires energy
  17. 17. Bulk Transport – requires energy
  18. 18. The Nucleus
  19. 19. Mitochondrion
  20. 20. Ribosomes • Ribosomes are cell organelles consisting of RNA and proteins, found in the cytoplasm and sometimes along the endoplasmic reticulum (RER). • Ribosomes are responsible for assembling the proteins in a cell.
  21. 21. Nucleus with Rough Endoplasmic Reticulum (RER)
  22. 22. Lysosomes
  23. 23. Lysosomes • Lysosomes serve as the cells digestive system. • They are membrane-bound organelles containing enzymes that can break down individual proteins or complete micro-organisms. • They are released from the golgi apparatus.
  24. 24. Chloroplasts in plant cells
  25. 25. Cytoskeleton • The centrosome (in animal cells) creates microtubules that provide a spindle for mitosis and meiosis.
  26. 26. Image Sources • http://commons.wikimedia.org/wiki/File:Prokary ote_cell_diagram.svg • http://commons.wikimedia.org/wiki/File:Animal_ cell_structure_en.svg • http://commons.wikimedia.org/wiki/File:Plant_c ell_structure.png • http://commons.wikimedia.org/wiki/File:Osmotic _pressure_on_blood_cells_diagram.svg • http://commons.wikimedia.org/wiki/File:1215_C ell_Membrane_Channels.jpg
  27. 27. Image Sources • http://commons.wikimedia.org/wiki/File:Cell_ membrane_detailed_diagram_en.svg • http://commons.wikimedia.org/wiki/File:Diffu sion.en.svg • http://commons.wikimedia.org/wiki/File:Cent rosome_(standalone_version)-en.svg • http://commons.wikimedia.org/wiki/File:Endo cytosis_types.svg

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