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Passive Transport-Osmosis/Diffusion
Cell Membrane Passive Transport-Osmosis/Diffusion
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What is the cell membrane?
A thin, flexible barrier This regulates what enters and leaves the cell and also provides protection and support, selectively permeable. Small, nonpolar molecules pass through best
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What is it made of? It is made up of a double-layered sheet called the lipid bilayer. The cell membrane is also made up of proteins and carbohydrates. Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains
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Cell membrane is said to be like a MOSAIC—WHY?
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How is a window screen similar to a cell membrane?
1. What are some things that can pass through a window screen? 2. What are some things that cannot pass through a window screen? Why is it important to keep these things from moving through the screen? 3. The cell is surrounded by a cell membrane, which regulates what enters and leaves the cell. Why is it important to regulate what moves into and out of a cell?
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Hydrophillic- having a strong affinity for water
Hydrophobic- Repelling, tending not to combine with, or incapable of dissolving in water. Hydrophillic- having a strong affinity for water Cell membranes are made of a phospholipid bilayer Phospholipids have a hydrophillic head and 2 hydrophobic tails. *The hydrophobic tails will want to stay away from water *The hydrophillic heads want to be near water. Bilayer- Two layers of phospholipids with the tails facing the center of the layer and the heads facing outward. Water loving (polar) Water-repelling (nonpolar)
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The Cell Wall Main function is to provide support and protection—mostly in plant cells Allow water, oxygen, CO2 through Made of mostly cellulose
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Cell Membrane Exit Slip
How is the cell membrane similar to a plastic bag? What does it mean to be a selectively permeable membrane? What two compounds make up a cell membrane? What does hydrophobic mean? What does hydrophilic mean? Draw a phospholipid bilayer
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Diffusion-Passive Transport
Cells exist in a LIQUID environment Diffusion is the movement of particles from high concentration to lower concentration Diffusion does NOT require the use of energy When concentrations on both sides are the same, equilibrium is reached. Diffusion still occurs when equilibrium is reached.
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Osmosis The diffusion of water across a selectively permeable membrane
Isotonic-concentrations of water/sugar are same on both sides Hypertonic—Higher solute concentration outside the cell Hypotonic—Lower solute concentration outside the cell
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Hypotonic Solutions Fewer solutes than in the cell Water moves into the cell Cell will swell and can burst Isotonic Solutions Solutes are equal to the cell Water is in equilibrium; moving in and out equally. Cell LIVES! Hypertonic Solutions More solutes than in the cell. Water moves out of the cell Cell will shrivel and possibly die
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Facilitated Diffusion
Larger molecules such as glucose can pass through protein channels in cell membrane Different channels allow different molecules to pass. Still will only occur from high to low concentration High Concentration Cell Membrane Low Concentration
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Passive Transport – is the facilitative diffusion of particles through the cell membrane from a region of high concentration to an area of low concentration. No energy is needed for this process. Cell Membrane Cytoplasm
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2. Active Transport – is the diffusion of particles through the cell membrane from a region of low concentration to a region of high concentration. ATP and a carrier molecule are required for this process. Cell Membrane ATP Cytoplasm
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Facilitated Diffusion Concentration Gradient
Osmosis Facilitated Diffusion Concentration Gradient High to Low Particle Moving Any small particle Water Large particles Energy Requirement None Key Terms Concentration and Equilibrium Hypertonic, Isotonic, Hypotonic Channel Protein
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Passive Transport Exit Slip
In your own terms, describe the following terms: Diffusion Osmosis Facilitated Diffusion Does passive transport require energy? Which way do particles move across the concentration gradient during passive transport. Label the following pictures as isotonic, hypertonic or hypotonic 50% Water 50% Salt 20% Water 80% Salt 70% Water 30% Salt 50% Water 50% Salt 80% Water 20% Salt 30% Water 70% Salt
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