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http://www.youtube.com/watch?v=aSfoB8Cmic&feature=relmfu http://www.youtube.com/watch?v=ULR79TiUj80&feature=r elated Cell Membrane and its types of Transport About Cell Membranes 1.All cells have a cell membrane 1. Functions: a. Provides protection and support for the cell b. Controls what enters and exits the cell to maintain an internal balance TEM picture of a real cell membrane. LIPID BILAYER About Cell Membranes (continued) 3.Structure of cell membrane Lipid Bilayer is made up of many small Phospholipids a.The head is hydrophilic or water loving b. The tail is hydrophobic or water fearing. c.Proteins embedded in membrane Phospholipid Lipid Bilayer Heads of the bilayer love water. Tails of the bilayer hide from water. Lipid Bilayer Proteins The Cell Membrane About Cell Membranes (continued) Cell Membrane (aka Plasma Membrane) • Controls the movement of molecules in and out of the cell • Selectively Permeable Selectively Permeable • A membrane that allows only certain things to pass through Transport Types of Transport Passive Active DOESN’T REQUIRE ENERGY REQUIRES ENERGY Passive Transport Passive Particles passes through the cell from a more crowded area to a less crowded area. Concentration How much stuff there is High Concentration Low Concentration Passive Transport The passive movement of material from an area of high concentration to an area of low concentration Passive Transport Movement of materials that DOES NOT require energy What happens to Kool-Aid crystals over time??? Diffusion The movement of PARTICLES through a selectively permeable membrane from an area of high particle concentration to low particle concentration Solution Solute = substance being dissolved Solvent = dissolves another substance Solution Diffusion Diffusion Diffusion, which way will the particles move? Diffusion: does moving the molecules in this direction require energy? Types of Passive Transport • Diffusion • Osmosis • Facilitated diffusion • NONE OF THESE REQUIRE ENERGY Types of Passive Transport • Diffusion • Osmosis • Facilitated diffusion • NONE OF THESE REQUIRE ENERGY OSMOSIS The movement of water through a selectively permeable membrane from an area of high water concentration to low water concentration OSMOSIS Purpose: so cells can maintain BALANCE with their environment Maintains Homeostasis Concentration of Water: Which is 100% higher? 75% Water 50% Water and 50% Sugar Water and 25% Salt 50% Water and 50% Salt 75% Water and 25% Salt 100% Water Hypotonic • Concentration of water INSIDE a cell is SMALLER than concentration of water outside a cell • Which direction will water move? 100% Water 50% Water and 50% Sugar 100% Water 50% Water and 50% Sugar Will the cell increase or decrease in size? Hypertonic • Concentration of water INSIDE a cell is LARGER than concentration of water outside a cell • Which direction will water move? Hypertonic 75% Water and 25% Salt 100% Water Will the cell increase or decrease in size? Isotonic • Concentration of water INSIDE a cell is the SAME as water outside a cell. • What direction will water flow? Isotonic 50% Water and 50% Salt 50% Water and 50% Sugar Will the cell increase or decrease in size? 1.Hyp0tonic, 2.Hypertonic, or 3.Isotonic? 100% Hypotonic 100% Water Water 50% Water and 50% Sugar 100% Water 50% Water and 50% Salt Isotonic 75% Water and 25% Salt Hypertonic 1.Hypotonic, 2.Hypertonic, or 3.Isotonic? Isotonic 50% Water 50% Sugar 50% Water and 50% Sugar 75% Water and 25% Salt Hypertonic 100% Water Water flow in or out? 100% Water 50% Water and 50% Sugar 100% Water 100% Water 50% Water and 50% Salt 75% Water and 25% Salt Water flow in or out? 50% Water 50% Sugar 50% Water and 50% Sugar 75% Water and 25% Salt 100% Water Osmosis 80% water 30% salt 95% water 5% salt Osmosis 80% water 30% salt 95% water 5% salt Osmosis 95% water 5% salt 75% water 20% salt Osmosis 95% water 5% salt 75% water 20% salt Types of Passive Transport • Diffusion • Osmosis • Facilitated Diffusion • NONE OF THESE REQUIRE ENERGY Facilitated Diffusion • Why facilitated diffusion? • When materials cannot move through the cell membrane, it gets help from a protein channel. • But it is still a type of passive transport because? Facilitated diffusion Channel Proteins allow specific molecules through. NO ENERGY REQUIRED! High Concentration Low concentration through a protein channel Facilitated Diffusion Facilitated Diffusion: still move from high to low Facilitated Diffusion: still move from high to low What are the 3 types of Passive transport?? 3 types of passive transport • Diffusion • Osmosis • Facilitated Diffusion Active Transport Active REQUIRES ENERGY Active Transport Movement of materials from low concentration to high concentration using a protein carrier that requires energy Active Transport Requires ENERGY to happen– the cell has to work for it. Carrier Proteins make it happen. Active Transport Active transport: Which way will the molecules move? Does moving the molecules in this direction require energy? Active Transport Active Transport Types of Active Transport • Endocytosis • Exocytosis Endocytosis Process of bringing particles into a cell using extensions of the cellular membrane To determine endocytosis 1. Particle starts OUTSIDE the cell. 2. Cell membrane wraps around particle. 3. Particles end INSIDE the cell. • FROM THE OUTSIDE TO THE INSIDE !! Exocytosis Process of moving particles out of a cell by fusing a vesicle to the cell membrane (how wastes are excreted from cells) To determine exocytosis 1. Particle starts INSIDE the cell, in a vesicle. 2. Vesicle fuses with cell membrane. 3. Particles are released and end up OUTSIDE the cell. FROM THE INSIDE TO THE OUTSIDE Endocytosis vs. Exocytosis Check for understanding • Active transport moves molecules from an area of ______________ concentration to __________ concentration • Passive transport moves molecules from an area of ______________ concentration to __________ concentration How do you determine Active or Passive? 1. You count the number of particles inside, then outside. 2. Label MORE or LESS on both sides. 3. Passive – the arrow goes from more to less Active- the arrow goes from less to more. Active or Passive? Active or Passive? Diffusion is the movement of particles from ________ concentration to __________ concentration across the membrane. Osmosis is the movement of __________ across the membrane from high concentration to low concentration. Osmosis 95% water 5% salt 75% water 20% salt Facilitated Diffusion The movement of molecules from ________ concentration to ________ concentration with the help of a _______________. Does this require energy? What are the three types of passive transport? Passive Transport • Diffusion • Osmosis • Facilitated diffusion Endocytosis: particles _______ the cell when the cell membrane wraps around the particle and pushes it in. A. B.