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Cellular Transport About Cell Membranes 1.All cells have a cell membrane 2.Functions: a.Controls what enters and exits the cell to maintain an internal balance called homeostasis b.Provides protection and support for the cell About Cell Membranes (continued) Lipid Bilayer -2 layers of phospholipids draw a.Phosphate head is polar (water loving) b.Fatty acid tails non-polar (water fearing) Phospholipid Polar heads Fluid Mosaic love water Model of the & dissolve. cell membrane Non-polar tails hide from water. Carbohydrate cell markers Proteins Membrane movement animation About Cell Membranes (continued) • 4. Cell membranes have pores (holes) in it a.Selectively permeable: Allows some molecules in and keeps other molecules out b.The structure helps it be selective! Pores Structure of the Cell Membrane Outside of cell Proteins Lipid Bilayer Transport Protein Animations of membrane Go to structure Section: Carbohydrate chains Phospholipids Inside of cell (cytoplasm) Types of Cellular Transport •Animations of Active Transport & Passive Transport • Weeee!! ! Passive Transport cell does not use energy 1. Diffusion 2. Facilitated Diffusion 3. Osmosis • high low Active Transport cell does use energy 1. Protein Pumps 2. Endocytosis 3. Exocytosis This is gonna be hard work!! high low Passive Transport • • • cell uses no energy molecules move randomly Molecules spread out from an area of high concentration to an area of low concentration. • (HighLow) • Three types: 3 Types of Passive Transport 1. Diffusion – substances pass directly through the cell membrane 2. Facilitated Diffusion – diffusion with the help of transport proteins 3. Osmosis – diffusion of water Passive Transport: 1. Diffusion Simple Diffusion Animation 1. Diffusion: random movement of particles from an area of high concentration to an area of low concentration. (High to Low) • Only small, non-polar molecules can pass directly through the cell membrane – Ex. O2, CO2 http://bio.winona.edu/berg/Free.htm Simple diffusion video Passive Transport: 2. Facilitated Diffusion A 2. Facilitated diffusion: diffusion of specific particles through transport proteins found in the membrane a.Transport Proteins are specific – they “select” only certain molecules to cross the membrane b.Transports larger or charged molecules Facilitated diffusion (Channel Protein) Carrier Protein B Diffusion (Lipid Bilayer) Transport Proteins Channel Proteins • Like a tunnel in the cell membrane, that certain substances may pass through. Carrier Proteins • Substances bind and the protein changes shape to transport the substance across the cell membrane. Review Questions • What are the two types of transport? What is the difference between them? • What is the cell membrane composed of? • In what type of diffusion can substances pass directly through the phospholipid bilayer? • Compare and contrast channel and carrier proteins. Passive Transport: 2. Facilitated Diffusion Glucose molecules Cellular Transport From aHigh Concentration High • Channel Proteins animations Cell Membrane Low Concentration Through a Go to Section: Transport Protein Protein channel Low Passive Transport Video Passive Transport: 3. Osmosis Osmosis animation • 3.Osmosis: diffusion of water through a selectively permeable membrane • Water moves from high to low concentrations Drinking Sea Water Video •Water moves freely through specialized proteins call aquaporins. •Solute (green) to large to move across. Effects of Osmosis on Life • Osmosis- diffusion of water through a selectively permeable membrane • Water is so small and there is so much of it the cell can’t control it’s movement through the cell membrane. • Hypertonic Solution Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. inside cell = ↑ [water] outside cell = ↓ [water] shrinks Result: Water moves from inside the cell into the solution: This causes the Cell to SHRINK (Plasmolysis)! • Isotonic Solution Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. inside cell = [water] same inside & out outside cell = Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium) • Hypotonic Solution Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. inside cell = ↓ [water] outside cell = ↑ [water] Result: Water moves from the solution into the cell. This causes the Cell to Swell and bursts open (cytolysis)! What type of solution are these cells in? A B C Hypertonic Isotonic Hypotonic How Organisms Deal with Osmotic Pressure •Bacteria and plants have cell walls that prevent them from over-expanding. In plants the pressure exerted on the cell wall is called turgor pressure. • Salt water fish pump salt out of their specialized gills so they do not dehydrate. • Animal cells are bathed in blood. Kidneys keep the blood isotonic by remove excess salt and water. Osmosis Problems: Draw the cell and use arrows to show the movement of water • 1. If a cell contains 45% water and it is in a solution of 25% water, will water move into or out of the cell? What type of solution is this? • 2. If a cell contains 55% salt and it is in a solution of 25% salt which way will water move? What type of solution is it? • 3. If a cell contains 45% salt and the solution is 45% salt which way will water move and what type of solution is it? TOTD: Osmosis Questions 1. In osmosis, water always moves toward the ____ solution: that is, toward the solution with the____ solute concentration. • a. isotonic, greater • b. hypertonic, greater • c. hypertonic, lesser • d. hypotonic, greater • e. hypotonic, lesser 2. Why do you think sea water is dangerous to drink? Explain using your knowledge of osmosis. Active Transport •Cell uses energy • Moves materials against the concentration gradient. From a Low concentration to a High concentration. •(Low High) •Three Types: Types of Active Transport Sodium Potassium Pumps (Active Transport using proteins) 1. Protein Pumps require energy to do work such as move substances from low to high concentrations (going uphill) •Example: Sodium / Potassium Pumps are important in nerve responses. Protein changes shape to move molecules: this requires energy! Types of Active Transport • 2. Endocytosis: taking bulky material into a cell • Uses energy • Cell membrane folds in around food particle • “cell eating” • forms food vacuole & digests food • This is how white blood cells eat bacteria! Types of Active Transport 3. Exocytosis: Forces material out of cell in bulk • membrane surrounding the material fuses with cell membrane • Cell changes shape – requires energy • EX: Hormones or wastes released from cell Endocytosis & Exocytosis animations Review 9/15 • Draw the concept map on a separate sheet of paper and use your notes to fill in the blanks. Review of Active Transport • Protein Pumps • Sodium Potassium Pump Animation This powerpoint was kindly donated to www.worldofteaching.com http://www.worldofteaching.com is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.