BIO 201 1st Edition Lecture 12 Outline of Last Lecture I. Muscle ContractionA. MyosinII. TransportA. KinesinB. DyneinOutline of Current Lecture I. Plasma MembraneA. Membrane FunctionB. Membrane Structure II. Membrane FluidityA. Fluid Mosaic ModelB. FRAPIII. Evolution Of MulticellularityCurrent LectureI. Plasma MembraneA. Function:-Compartmentalization- creates order from disorder, maintains correct intracellular environments-Scaffolding- efficiency of cellular functions-Selective barrier to diffusion- allows only certain molecules to pass - Active transport- transport of specific substances across membranes -Signaling- Outside signal cellular response-Intercellular (GAP) Junction- connection between cells directly -Energy/Metabolism- production of ATP-Electrical transduction- propogationof electrical signals (neurons/ muscle)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.B. Structure- 70-80 angstroms thick= ~2x length of typical phospholipid-railroad structure appearance in transmission electron microscopyII. Membrane Fluidity- Fluid mosaic model-Unsaturated phospholipids more fluid-Saturated phospholipids less fluid-Organisms adapting to low temps have more unsaturated fatty acids, vice versa.-Cholesterol is essential to life, 25% of all lipids in membranes are cholesterol-Cholesterol has a high melting temp when in high temperatures, but at low temperatures cholesterol interferes with side chain interaction A. Fluid Mosaic Model-Phospholipids are amphipathic (both non-polar and polar)-Membrane asymmetry- lipids, proteins, and carbs are asymmetrical in the membrane-Membrane fluidity- Lipid bilayer is a fluid enabling protein to float around B. FRAP- Fluorescence Recovery After Photobleaching-Unbleached cells label lipids/proteins with fluorescent dyebleach spot with laser unbleached proteins/lipids diffuse and fill in spot-FRAP can be graphed, steep curve= fast recovery, high fluidity -Patches of very low fluidity = LIPID DRAFTS;-More saturated phospholipids-Some specialized high melting temp. phospholipids -Longer fatty acid chains on phospholipids -More cholesterol -Proteins with relatedfunction localize in lipid raftsimproved efficiencyIII. Evolution of Multicellularity-“Dicty” is unicellular when food is available, when food runs outs Dicty cells aggregate, extend upwards, form a fruiting body, and release spores-To accomplish multicellularity, cells must be:-Able to create boundary, protecting organism fromenvironment -Able to create a stable, multicellular structure -Communicate with each other-Regenerate new individuals from germ
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