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UofL BIOL 240 - Membrane Transport and Functions

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BIOL 240 1st Edition Lecture 7Outline of Last Lecture Parts of the CellI. The Endoplasmic Reticuluma. Rough ERb. Smooth ERII. The Golgi ApparatusIII. LysosomesIV. VacuolesV. Endomembrane SystemVI. Chloroplasts and Mitochondriaa. Two cellular power stations:i. Chloroplastsii. Mitochondriab. ChloroplastsVII. Evolutionary Origins of EukaryotesVIII. The Cytoskeletona. RolesIX. Cell Junctions in Animal CellsX. Cell Walls of PlantsXI. AntibioticsOutline of Current Lecture I. OverviewII. PhospholipidsIII. Types of Phospholipid TailsIV. CholesterolV. Membrane Proteinsa. Integral vs. Peripheral ProteinsVI. Synthesis and Sidedness of MembranesVII. The Permeability of the Lipid BilayerVIII. Transport Proteinsa. Carrier proteinsb. SpecificityThese 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.IX. DiffusionX. OsmosisXI. Tonicitya. Animal Cellb. Plant CellXII. Facilitated DiffusionXIII. Active Transporta. The sodium-potassium pumpXIV. Bulk Transporta. Exocytosisb. EndocytosisXV. Cell SignalingCurrent LectureI. Overviewa. The plasma membrane separates the living cell from its surroundingsb. Selective permeabilityi. Insides stay inii. Outsides stay outiii. Let certain stuff acrossII. Phospholipidsi. Most abundant lipid in most membranesii. Amphipathic molecule: has two opposite sides (hydrophilic and hydrophobic)iii. Lateral movement in membraneIII. Types of Phospholipid Tailsa. Viscous: saturated tails pack togetherb. Fluid: unsaturated tails prevent packingIV. Cholesterola. At warm temperatures, cholesterol restrains movement of phospholipidsb. At cool temperatures, cholesterol prevents packingV. Membrane Proteinsa. Proteins determine most of the membrane’s specific functionsb. Integral vs. Peripheral Proteinsi. Integral: goes all the way across the membraneii. Peripheral: does not go all the way through; remains on ends1. Transport, enzymatic activity, cell-cell recognition, intercellular joining, signal transduction, attachment to the cytoskeleton and intercellular matrixVI. Synthesis and Sidedness of Membranesa. Membranes have distinct inside and outside facesb. Asymmetrical distribution of proteins, lipids, and carbohydratesc. Determined when the membrane is built by ERVII. The Permeability of the Lipid Bilayera. Nonpolar, small molecules cross easilyi. Hydrocarbonsb. Polar, large molecules do not cross easilyi. Sugarsii. Large: break the membraneiii. Polar: thermodynamically unfavorableVIII. Transport Proteinsa. Carrier proteinsi. Integral membrane proteins that allow large/polar molecules to get acrossii. Uncharged, nonpolar amino acids are on outsideiii. Charged, polar molecules amino acids are on inside (hydrophilic)b. SpecificityIX. Diffusiona. Moving across the membrane with the concentration gradienti. From high concentration to lowb. Dynamic equilibrium: when concentration becomes equalc. Passive transport: does not require energyX. Osmosisa. Diffusion of waterb. Water moves towards higher concentrationXI. Tonicitya. Animal Celli. Lysed cell: Hypotonic: salt concentration inside of cell is greater than outside (water goes into cell)ii. Normal cell: Isotonic: salt concentration inside of cell equals the outsideiii. Shriveled cell: Hypertonic: salt concentration inside of cell is less than outside (water goes out of cell)b. Plant Celli. Turgid (normal) cell: Hypotonic: water goes into cellii. Flaccid cell: Isotonic: water goes into and out of cell at the same rateiii. Plasmolyzed cell: water goes out of cellXII. Facilitated Diffusiona. Uses transport/channel proteinsb. Proteins includei. Aquaporin: water moving acrossii. Ion channel: ions moving acrossXIII. Active Transporta. Moves substances against concentration gradientsb. Requires energyc. Maintain concentration gradients that differ from their surroundingsd. The sodium-potassium pumpi. Cytoplasmic Na+ bindsii. Stimulates ATP phosphorylationiii. Change in protein shapeiv. High affinity for K+, release of phosphatev. Restores the proteins original shapevi. K+ is released; cycle repeatsXIV. Bulk Transporta. Small solutes and waterb. Vs. large molecules such as polysaccharides and proteinsc. Requires energyd. Exocytosis: bringing stuff outside of celle. Endocytosis: bringing stuff inside of cellXV. Cell Signalinga. Cell-to-cell communicationb. Allows multicellular organisms to coordinate activitiesc. Also essential for many multicellular organismsi. Quorum signaling: group collaborationd. Kinases: adds phosphate groups to moleculese. Phosphatases: takes phosphate groups from


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