Presentation on theme: "Target VII Identify and describe the functions of the component structures of the plasma membrane: phospholipid, integral protein, peripheral protein,"— Presentation transcript:
1 Target VIIIdentify and describe the functions of the component structures of the plasma membrane: phospholipid, integral protein, peripheral protein, cholesterol, hydrophilic head (polar), hydrophobic tails (non-polar), glycolipids, and glycoproteins.
2 The Cell MembraneComposed of macromolecules: phospholipids, proteins, and carbohydratesIs selectively permeable . . .Phospholipid bilayer is amphipathicHydrophobic hydrocarbon tailsHydrophilic phosphate headsStructure and movement of cell membrane is described as the FLUID MOSAIC MODEL
3 I. FLUIDITY of MembraneA. Lipids and proteins move laterally within the membraneB. Fluidity depends upon a variety of factors:Type of hydrocarbon tailsTemperaturePresence of cholesterolComposition of lipids and proteins within the membrane (dynamic)Whether membrane components are attached to ECM or cytoskeleton
4 I. FLUIDITY of MembraneC. Proper functioning of membrane depends upon membrane fluidityFluidity can be altered by changing composition and quantity of proteins and/or lipids within membrane-->Adaptations of plants and smaller vertebrates to cold temperatures in winter
5 II. Mosaic:assortment of various proteins w/in membrane PROTEINS determine function(s) of membraneIntegral Proteins*transmembrane protein*describe the domain (portion) of the protein that is embedded within the membrane2. Peripheral Proteins*If inside cell, held in place by cytoskeleton*If outside cell, held in place by Extracellular matrix (ECM)3. One protein may have multiple functions OR several different proteins are required in a membrane to accomplish cellular tasks
7 II. Mosaic:assortment of various proteins w/in membrane B. Carbohydrates are located on the exterior surface of plasma membraneCells communicate with and recognize each other by the types of CHO on their exterior plasma membrane surface (ex: A, B, O blood types)Oligosaccharides may be bound to lipids or proteins (oligo- = Few; ~15 monosaccharides)a. Glycolipid b. Glycoprotein
9 Target VIIIUse representations, models, and/or data to analyze situations in which molecules move passively by diffusion, osmosis, or facilitated diffusion.
10 III. Movement Across Membranes Membrane is selectively permeableWhat does selectively permeable mean?Name examples of molecules that CAN pass thru cell membrane… WHY can they pass thru?Name examples of molecules that CANNOT pass thru c.m WHY can’t they?Functions of membrane proteinsTransport: water, ions, glucoseEnzyme Activity: cellular respiration, photosynthesisSignal Transduction: bind protein hormoneIntercellular joining: tight &/or gap junctions, desmsomesCell to Cell Recognition: glycoproteinsAttach cell to ECM and/or cytoskeletonAll transport proteins must be ________, because….
12 IV. Passive TransportMovement of molecules down concentration gradient; from high [ ] to low [ ]Membrane must be permeable for molecules to diffuseOnce equilibrium is reached, NET molecular movement is EQUAL both into and out of cell**molecules DO NOT stop moving**Diffusion HAPPENS (no energy required!)Diffusion of one type of molecule occurs independent of another molecule if they’re both permeable; direction of diffusion for each molecule depends upon [ ] of a particular molecule across membraneF. Can be: Diffusion, Facilitated Diffusion, Osmosis
13 V. Facilitated Diffusion A. ‘Help’ polar and charged molecules across membrane thru transport (integral) proteins1. Recall transport proteins are specific to molecules they move (like enzyme/substrate specificity)2. Transport proteins can be saturated therefore, they have a maximum rate of moving stuff due to limited # of proteins within membrane3. Transport proteins can be inhibited4. ‘Catalyze’ physical movement of stuff that would not be able to cross membraneMolecules move down concentration gradientAQUAPORINS: transport protein for waterGATED CHANNELS: stimulus (electrical or chemical), cause opening & closing--> stimulus causes change of protein shape
14 V. Facilitated Diffusion Examples of gated channels:Ligand-gatedVoltage-gatedMechanically-gated
15 VI. Osmosis (a type of passive transport) Movement of WATER from high [water] to low [water]Water follows solutes… water moves from area of low [solute] to area of high [solutes]Direction of water movement depends upon [ ] of water and solutes across a membrane between a cell and solution (environment)Osmosis and CellsAnimal CellPlant Cell
16 Plant & Animal Cell Osmosis Review hypotonic solution-->low [solute] in solution compared to cellanimal cell: lysed Lplant cell: turgid JB. HYPERTONIC solution:-->high [solute] in solutionn compared to cellanimal cell: crenate Lplant cell: plasmolysed LC. ISOTONIC solution: =[solute] in solution & cellanimal cell: normal Jplant cell: flaccid K
18 VI. Osmosis Water balance for Osmoregulators In cells WITHOUT cell walls (animals, protists)•MUST control amount of water entering and leaving cell if not in an environment that is isotonic to cell = osmoregulate•Osmoregulators use ENERGY to maintain internal osmotic balance different from the surrounding environment•example: Paramecium contractile vacuole-->The pond in which the Paramecium lives is ______to the cell, so water moves ______ and cell has to use energy to pump water ______ the cell
20 VI. Osmosis 2. In cells WITH cell walls (plants, fungi, bacteria) Water balance for Osmoregulators2. In cells WITH cell walls (plants, fungi, bacteria)•Cells prefer to be in a HYPOTONIC solution because water enters cells and pressure of extra water in vacuole pushes against cell walls.•The water pressure in the vacuole is exterted onto and by nearby cells which makes cells TURGID - very firm so plant structures (stems, leaves) stand upright :)•In isotonic solution cells lack adequate ‘push’ from water in nearby cells…FLACCID-plants wilt, droop:|•In hypertonic solution, cell wall NOT an advantage, cell shrinks and plasma membrane pulls away from cell wall…PLASMOLYSIS - lethal to cell :(
21 Target IXUse representations, models, and/or data to analyze situations in which molecules move actively to establish concentration gradients across a membrane or move large molecules into or out of a cell (endocytosis and exocytosis).
23 VII. CO-TRANSPORT (active transport) SYMPORT (Active, Indirect) ANTIPORT (Active, Direct)Hyperlink to Animation
24 How do macromolecules enter or exit cells How do macromolecules enter or exit cells? How do large quantities of substances enter or exit cells?There are FOUR ways!
25 IIX. EXOCYTOSISA. Secrete large molecules out of cellB. Cellular vesicles fuse with plasma membraneC. Process of fusion repairs / replaces cell membraneD. Process deposits proteins from inside surface of vessicle membrane to outer surface of cell membrane b/c vesicle turned inside out as it becomes part of plasma membraneE. Therefore, exocytosis ensures the plasma membrane will display its characteristic CELL SURFACE proteins which dictate membrane function
26 IX. ENDOCYTOSISA. Phagocytosis: cell eatingMore animationsB. Pinocytosis: cell drinkingAnother animation of pinocytosisX. Receptor Mediated Endocytosis-->Intake of specific molecules, regardless of their concentration, due to specificity and affinity of ligand (binding molecule) to it’s ligand-receptor protein on cell surface-->Example Animation: Cholesterol Metabolism