Cellular Transport PDF

Cellular Transport At the end of the lesson, students are expected to: Describe the structural components of the cell membrane Relate the structure and composition of the cell membrane to its function Explain transport mechanisms in cells (diffusion, osmosis, facilitated transport, ac...

Cellular Transport At the end of the lesson, students are expected to: Describe the structural components of the cell membrane Relate the structure and composition of the cell membrane to its function Explain transport mechanisms in cells (diffusion, osmosis, facilitated transport, active transport) Differentiate exocytosis and endocytosis  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 TEM picture of a b.Provides protection and real cell membrane. support for the cell  About Cell Membranes (continued) 3.Structure of cell membrane Lipid Bilayer -2 layers of phospholipids a.Phosphate head is polar (water loving) Phospholipid b.Fatty acid tails non-polar (water fearing) c.Proteins embedded in membrane Lipid Bilayer  Polar heads Fluid Mosaic love water Model of the & dissolve. cell membrane Non-polar Membrane movement tails hide animation from water. Carbohydrate cell markers Proteins  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 Carbohydrate Proteins chains Lipid Bilayer Transport Protein Phospholipids Inside of cell Animations (cytoplasm) of membrane Go to structure Section:  Animations of Active Types of Cellular Transport Transport & Passive Transport Weeee!! Passive Transport ! cell doesn’t use energy 1. Diffusion high 2. Facilitated Diffusion 3. Osmosis low Active Transport This is cell does use energy gonna be hard 1. Protein Pumps work!! high 2. Endocytosis 3. Exocytosis 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. (High→Low) Three types: 3 Types of Passive Transport 1. Diffusion 2. Facilitative Diffusion – diffusion with the help of transport proteins 3. Osmosis – diffusion of water  Passive Transport: Simple Diffusion Animation 1. Diffusion 1. Diffusion: random movement of particles from an area of high concentration to an area of low concentration. (High to Low) Diffusion continues until all molecules are evenly spaced (equilibrium is reached)-Note: molecules will still move around but stay spread out. http://bio.winona.edu/berg/Free.htm  Passive Transport: 2. Facilitated Diffusion A B 2. Facilitated diffusion: diffusion of specific particles through transport proteins found in the membrane a.Transport Proteins are Facilitated Diffusion specific – they “select” diffusion (Lipid only certain molecules (Channel Bilayer) to cross the membrane Protein) b.Transports larger or charged molecules Carrier Protein  Passive Transport: 2. Facilitated Diffusion Glucose molecules Cellular Transport From a- High High Concentration Channel Proteins animations Cell Membrane Protein Low Concentration channel Low Transport Through a → Go to Protein Section:  Passive Transport: Osmosis 3. Osmosis animation 3.Osmosis: diffusion of water through a selectively permeable membrane Water moves from high to low concentrations Water moves freely through pores. Solute (green) to large to move across.  Active Transport cell uses energy actively moves molecules to where they are needed Movement from an area of low concentration to an area of high concentration (Low → High) Three Types:  Sodium Potassium Pumps Types of Active Transport (Active Transport using proteins) 1. Protein Pumps - transport proteins that require energy to do work Example: Sodium / Potassium Pumps are important in nerve Protein changes responses. shape to move molecules: this requires energy! Types of Active Transport 2. Endocytosis: taking bulky material into a cell Uses energy Cell membrane in-folds 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 Endocytosis & Exocytosis material out of cell in bulk animations membrane surrounding the material fuses with cell membrane Cell changes shape – requires energy EX: Hormones or wastes released from cell  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.  Osmosis Animations for Hypotonic Solution isotonic, hypertonic, and hypotonic solutions Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!  Osmosis Animations for Hypertonic Solution isotonic, hypertonic, and hypotonic solutions Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) shrinks Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!  Osmosis Animations for Isotonic Solution isotonic, hypertonic, and hypotonic solutions Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium) What type of solution are these cells in? A B C Hypertonic Isotonic Hypotonic  How Organisms Deal Paramecium (protist) removing excess water with Osmotic Pressure video Bacteria and plants have cell walls that prevent them from over-expanding. In plants the pressure exerted on the cell wall is called tugor pressure. A protist like paramecium has contractile vacuoles that collect water flowing in and pump it out to prevent them from over-expanding. 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.