MEMBRANES-LIPIDSMajor Component of the Plasma membrane is a double layer ofPhospholipids.Hydrophilic heads of the phospholipids are located at the internal and external surfaces separating two aqueous regionsHydrophobic tails are located on the interior of the membranePhospholipids are able to move laterally – contributing to the fluidityUnsaturated hydrocarbon tails have kinks in them preventing over packing between adjacent molecules.Cholesterol reduces fluidity but prevents membrane solidification at cold temperatures.Embedded in the lipid layer are glycoproteins and glycolipids.MEMBRANE PROTEINS AND THEIR FUNCTIONSA membrane is a collage of different protein often grouped togetherProteins determine most of the membrane specific functionsAsymmetrical distribution of proteins – Membrane protein have specific inside and outside faces. Determined by if the protein is made by the ER or the GolgiPeripheral proteins are bound to the surface of the membraneIntegral proteins penetrate the hydrophobic coreTransmembrane proteins are integral proteins that span the membrane the hydrophobic regions of an integral protein consist of one or more stretches of non popular amino acids, often coiled into alpha helixesList of major proteinsTransportEnzymatic activitySignal transductionCell-cell recognitionIntercellular JoiningAttachment to the cytoskeleton and extracellular matrix (ECM)You have proteins that join on to things like fats or sugarsGlycoproteins (Blood type – A, B, C etc.)GlycolipidProteins allow substances to flow in and out of the cellHOW DOES HIV RECOGNIZE AND INFECT?HIV must bind to the immune cell surface protein CD4 and a co-receptor CCR5 in order to infect theRecognition based on the 3D structureTRANSPORT PROTEINSAllow passage of hydrophilic substances across the membrane. Specific for substance it movesChannel Proteins have a hydrophilic channel that certain molecules or ions can use as a tunnelExample: Aquaporin – Facilitate passage of waterCarrier Proteins bind to molecules and change shape to shuttle them across membraneIon Channels facilitate the diffusion of ionsSome Ion channels called gated channels open or close in response to stimulationAn electron pump is a transport protein that generates voltage across a membraneACTIVE TRANSPORTSodium potassium pump is one type of active transport systemMaintain large excess of Na+ ions outside and less K+ insideTransports 3Na+ to outside and 2K+ to insideATP interactions phosphorylate the pump causing change in conformationImportant contribution to action potential in nerve cellsFailure=Swelling and lysisBIO 112 1st Edition Lecture 6Outline of Last Lecture II. Golgi Apparatus III. Lysosomes a. Structure b. Function IV. Peroxisomes V. Vacuoles VI. Energy conversion VII. Mitochondria VIII. Chloroplast IX. Cytoskeleton a. Microtubules b. Intermediate filaments and microfilaments Outline of Current Lecture X. Membrane – Lipids XI. Membrane Proteins and their functions a. Peripheral Proteins b. Integral Proteins c. Transmembrane Proteins XII. How does HIV recognize and infect?XIII. Transport Proteins a. Channel Proteins b. Carrier Proteins c. Ion Channel d. Electron Pump 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.XIV.Active Transport Current Lecture MEMBRANES-LIPIDSMajor Component of the Plasma membrane is a double layer ofPhospholipids.Hydrophilic heads of the phospholipids are located at the internal and external surfaces separating two aqueous regions Hydrophobic tails are located on the interior of the membrane Phospholipids are able to move laterally – contributing to the fluidity Unsaturated hydrocarbon tails have kinks in them preventing over packing between adjacent molecules.Cholesterol reduces fluidity but prevents membrane solidification at cold temperatures. Embedded in the lipid layer are glycoproteins and glycolipids. MEMBRANE PROTEINS AND THEIR FUNCTIONS A membrane is a collage of different protein often grouped together Proteins determine most of the membrane specific functionsAsymmetrical distribution of proteins – Membrane protein have specific inside and outside faces. Determined by if the protein is made by the ER or the GolgiPeripheral proteins are bound to the surface of the membrane Integral proteins penetrate the hydrophobic core Transmembrane proteins are integral proteins that span the membrane the hydrophobic regions of an integral protein consist of one or more stretches of non popular amino acids, often coiled into alpha helixes List of major proteinsTransport Enzymatic activity Signal transduction Cell-cell recognition Intercellular Joining Attachment to the cytoskeleton and extracellular matrix (ECM)You have proteins that join on to things like fats or sugars Glycoproteins (Blood type – A, B, C etc.)Glycolipid Proteins allow substances to flow in and out of the cell - HOW DOES HIV RECOGNIZE AND INFECT?HIV must bind to the immune cell surface protein CD4 and a co-receptor CCR5 in order to infect the Recognition based on the 3D structure - TRANSPORT PROTEINS Allow passage of hydrophilic substances across the membrane. Specific for substance it moves Channel Proteins have a hydrophilic channel that certain molecules or ions can use as a tunnel Example: Aquaporin – Facilitate passage of water Carrier Proteins bind to molecules and change shape to shuttle them across membraneIon Channels facilitate the diffusion of ions Some Ion channels called gated channels open or close in response to stimulationAn electron pump is a transport protein that generates voltage across a membrane  ACTIVE TRANSPORT Sodium potassium pump is one type of active transport system Maintain large excess of Na+ ions outside and less K+ inside Transports 3Na+ to outside and 2K+ to inside ATP interactions phosphorylate the pump causing change in conformation Important contribution to action potential in nerve cells Failure=Swelling and lysis