Plasma Membrane Plasma Membrane Structure Phospholipid bi-layer Structure Phosphate Head – Hydrophilic Lipid Tail – Hydrophobic Glycoprotein/Glycolipids – Cell markers Carrier Protein – Passive and Active Structure Carbohydrate cell markers Proteins Phospholipid molecules Floating Mosaic Function of the Plasma Membrane - selectively permeable membrane - allows for communication between cells - provides the cell with a specific “marker” Plasma Membrane http://telstar.ote.cmu.edu/Hughes/tutorial/ cellmembranes/bil.swf Construction of the Cell Membrane - Learning Ac - Flash Player Installation Carrier Protein Passive Channel – Leakage channel Active Channel – Open and close to let larger molecules through - Uses Cellular energy (ATP) Channel Protein Particle Theory 1. All matter is made of particles 2. The particles are in constant motion (Kinetic motion of particles) 3. The closer the particles are together, the greater the attractiveness between them. Particle Theory Solids – definite shape and volume Liquids – definite volume but indefinite shape Gases – indefinite shape and volume Matter Cellular Transport Passive Transport – use no cellular energy A) Diffusion B) Osmosis C) Facilitated Diffusion A. Diffusion - Movement of particles from an area of High concentration to an area of Low concentration - Particles will move until they are evenly distributed in an Equilibrium - Particles continue random movement, but it has no affect on the equilibrium Diffusion B. Osmosis - special diffusion where water passes through a selectively permeable membrane from an area of High concentration to an area of Low concentration Osmosis Osmosis II C. Facilitated Diffusion - special diffusion that is made faster by using Passive Channels (leakage channels) - can result in a conformational change in the shape of the protein. Facilitative Diffusion Facilitated Diffusion II Facilitated Diffusion III Try these: 1. The plasma membrane consists of ___ layers. 2. The molecules that make up the plasma membrane are called ______ 3. The phosphate heads like water and are called ______. 4. The lipid tails don’t like water and are called ______. 5. Special protein molecules called _____ are found throughout the plasma membrane. 6. Cell markers called _______ are attached to the top of these protein molecules. 7. The Particle Theory states that all matter is made up of tiny particles and that they are in _________. 8. Cells need to move materials in and out to maintain a state of balance between what is inside and outside. This balance is called _______ 9. Cells move materials in and out in 2 ways. ___________ and ___________ 10. ________transport doesn’t require the cell to expend any energy. 11. ________ transport requires the cell to use some of it’s own energy stored in _____ 12. There are 3 types of Passive Transport ________, _________ and __________. 13. Movement of any particles from H to L is called ________. 14. Movement of water molecules from H to L is called ________. 15. Diffusion of particles that are helped by carrier protein is called __________. Review of Passive Transport Passive Transport Environments that Cells might find themselves in: A) Hypotonic Solutions – greater concentration of water OUTSIDE the cell B) Hypertonic Solutions – greater concentration of water INSIDE the cell C) Isotonic Solutions – even concentrations of water inside and outside the cell How will cells react in each?? Animal cells Hypotonic Solution - water moves into the cell (osmosis), the cell swells, and may burst (Cytolysis) Hypotonic Solution How will cells react in each? Animal cells Hypertonic – water moves from inside out and the cell shrivels and dehydrates Hypertonic How will cells react in each? Animal cells Isotonic – water moves in and out of the cell at the same rate (Random movement) Isotonic Another look: Solutions What about plant cells? Hypotonic – water moves in and Turgor Pressure in the cell increases. What about plant cells? Hypertonic – water moves out of the cell and turgor pressure drops - the plasma membrane pulls away from the cell wall and the cell wilts. Plasmolysis What about plant cells? Isotonic – water moves in and out at the same rate. Another look: Cellular Traffic Active Transport (uses ATP) A) Endocytosis B) Exocytosis C) Movement against the “concentration gradient”. Cellular Traffic A) Endocytosis – movement of large particles into a cell packaged in vesicles . The cell uses energy stored in ATP i) Phagocytosis - - cell engulfs a large food particle by wrapping it’s cytoplasmic arms around the particle Phagocytosis Cellular Traffic i) Pinocytosis – cell engulfs a smaller particle or water droplet into the cell by indenting the plasma membrane. The cell uses energy stored in ATP Pinocytosis Pinocytosis 2 Cellular Traffic B) Exocytosis – excreting materials from a cell packaged in vesicles. The cell uses energy stored in ATP. Exocytosis Exocytosis 2 Cellular Traffic C) Movement against the Concentration Gradient (L to H) Particles are drawn against the concentration gradient using active channels that open and close using cellular energy L to H L-H Cellular Transport Review Thirst Reflex Passive Transport Environments Drag and Drop Cell membrane Homeostasis All these examples of cellular traffic are designed to help the cell maintain a state of balance between the inside and the outside of the cell.
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