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Transcript
Monday 1/9/12 AIM: How is the structure of the plasma membrane related to its function? DO NOW: In complete sentences, explain why every cell has a cell membrane. Homework: Take home cell questions 120 DO NOW ANSWER The cell membrane regulates what enters and leaves the cell Construction of the Cell Membrane Wisconsin Online How is the cell membrane constructed? The cell membrane Plasma membrane Phospholipid bilayer 2 layers of phospholipids Embedded with proteins and cholesterol molecule Functions of the cell membrane Helps to maintain balance or homeostasis within the cell Boundary between cell and its environment Selectively permeable: allows some to pass and others are kept out Phospholipid Hydrophillic heads Hydrophobic tails Fluid Mosaic model Individual phospholipids are not bonded Fluid because phospholipids move within the membrane At the same time, proteins in the membrane also move among the phospholipids These proteins create a mosaic model Why is it important for the membrane to be partly hydrophobic and partly hydrophillic? Tuesday 1/10/12 AIM: How is the cell membrane a fluid mocaic? DO NOW: 1- List the other two names for the cell membrane 2- Explain the difference between hydrophillic and hydrophobic HOMEWORK: Take home test 21-40. ALL OF IT MUST BE DONE BY TOMORROW! Water soluble at the outer surfaces and insoluble at inner surfaces. H bonds form between water and hydrophillic heads Why does the membrane need cholesterol? Helps stabilize the membrane Help the hydrophobic tails move What is the difference between an integral and peripheral protein? Peripheral proteins: only sit on the surface of the membrane Integral protein: extend through both layers of phospholipid bilayer Membrane proteins Fibrous proteins: receptors Glycoproteins: cell to cell recognition or identification Pore proteins: passive transport Channel proteins: active transport Glyco protein Glyco: tells me that it is part carbohydrate Protein: part protein How does the structure of the membrane relate to its function? 1- hydrophobic tails create a barrier between inside and outside of the cell 2- hydrophillic heads allow small water soluble molecules to bond to the membrane 3- cholesterol creates small gaps for the molecules to “sneak” across the membrane 4- Membrane proteins help molecules move in and out of the cell 5- Glycoproteins allow the cell to rcognize and be recognized by other cells Why is the plasma membrane selectively permeable? Wednesday 1/11/12 AIM: How does the plasma membrane regulate movement of molecules into and out of the cell? DO NOW: In complete sentences explain what you would do in the following situation: You are at a dance that contains 100 kids within 1 hour the dance fills up with 800 kids and you can hardly move. What would you do and why? Construction of the Cell Membrane Wisconsin Online How do molecules move across the plasma membrane? Lipid soluble molecules cross the membrane with no help Other molecules use membrane proteins Transport Passive: molecules move from a high to low concentration Active: molecules move from low to high concentration Thursday 1/12/12 AIM: How do molecules move across the cell membrane? DO NOW: List the parts of the cell membrane Homework: 1- Work on topic 2 of the midterm review How does the concentration gradient determine if molecules will cross the cell membrane passively or actively? Transport across the membrane cytoplasm has different molecules and ions. Some easily pass through the plasma membrane into the cell. These include water, oxygen and glucose molecules, and sodium and chloride ions. Passive Transport Small lipid soluble molecules move from a crowded area to a less crowded area Down the concentration gradient – High concentration (lots of molecules) to low concentration (less molecules) No energy is required Size and solubility of molecules determine its ability to cross the membrane Solubility= what a molecule can dissolve in Passive transport Passive transport Simple diffusion Osmosis Facilitated diffusion Diffusion Movement is driven by concentration gradient Molecules move from an area of high concentration to low concentration Solute concentration is equal http://www.indiana.edu/~phys21 5/lecture/lecnotes/lecgraphics/di ffusion2.gif http://highered.mcgrawhill.com/sites/0072495855/student _view0/chapter2/animation__how _diffusion_works.html Facilitated diffusion Some molecules are too big to passively diffuse So they need the help of carrier proteins Transport is still driven by a concentration gradient What are the different types of transport? Passive and active How are passive and active transport different? Passive: driven by concentration gradient Active: driven by ATP Osmosis Simple diffusion of water From an area of higher concentration to a region where they are in a lower concentration Isotonic: equal movement of water into and out of cell Hypotonic solution: net water movement into the cell Hypertonic: net movement of water out of the cell Aim: Why does the cell use energy to move molecules across the cell membrane? Do Now: Use your table from yesterday or create a new table organizing the osmotic environments and the flow of water in each. In a third column of your table, draw a picture of each using an x to represent solute molecules and o to represent water molecules. How does the concentration gradient determine the direction of molecule movement across the cell membrane? Active transport Movement of substances against a concentration gradient From low to high Needs energy Membrane proteins use energy to move individual molecules How does active transport differ from facilitated diffusion? AIM: How does the cell use energy to transport molecules across the plasma membrane? DO NOW: Use the picture displayed to explain the process: How is active transport different from passive transport? Passive transport does not need energy to move molecules from high to low concentration Active Transport uses energy to move molecules against the concentration gradient Why is active transport necessary for homeostasis? Certain molecules need to enter or leave the cell against their concentration gradient Active transport Endocytosis: cell uses energy to carry molecules inside Exocytosis: remove contents from the cell Ion pumps Co-transport Active transport Endocytosis: intake of particles or fluids in to the cell Pinocytosis: cell drinking Phagocytosis: cell eating Phagocytosis in an ameba Ion Transport Cotransport movement of 2 solutes together often moves 1 solute passively & other actively Assessment In your notebooks draw the picture depicted below and explain how molecules move in the direction of the arrows