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Complete Exam Review

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Kenneth Yip

Exam Review Section 1 Lecture 13Cells change shape function and interactions This change could lead to disease and so must be controlled How Cells Organize Tissues Spatially 1 Membrane Trafficking 2 Cytoskeletal Networks 3 Cell Adhesion Membrane TraffickingFunction o Engage Environment o Celltocell communication example nerves o Acquiring resources example gut lining epitheliumMechanismdynamic change and control of plasma membraneCompartments for Trafficking vesicles ER Golgi endosomes lysozomesPathways o BiosyntheticSecretory Pathway o Endocytic PathwayPathway Principles 1 Polarized Trafficking Routes one end is different from another 2 Sorting Stations 3 Retrieval Mechanism and Balance of Routes matching endocytosis with exocytosis Secretory Pathways ExocytosisTypesConstitutive Secretory Pathway continuous exocytosis vesicle docks and fuses with plasma membranecontinuous pumpingRegulated Secretory Pathway cargo is stored in vesicles and only secreted by signal activationMechanisms of both pathways are similar o Cargo is concentrated into a vesiclebarrier still present o Vesicle docks and fuses removes barrierExample 1 Mast cell immune cell releases stored Histamine increases attack abilities after induction signal by a soluble extracellular stimulant in response to invasionRegulated Secretion o Cleavage Furrowduring cell division additional plasma membrane is needed the endosome in the cell provides phospholipids for the membrane through exocytosis o Phagocytosis endocytosis exocytosisendosome provides proteins to maintain plasma membrane o Wound Repair Lysosomes provide the phospholipid Endocytic PathwaysFunction to counterbalance exocytosis and perform specific functionsSteps of Endocytosis o Invagination o FissionOptions postendocytosis 1Recycling secreted in the same side 2 Transcytosis secreted in opposite side 3 Degradation goes to lysosome Endocytosis Example Cholesterol1 LDL lowdensity lipoprotein in blood binds to LDL receptor 2 Endocytosis of LDLLDL Receptor a Invagination with coated put b Fission of coated vesicle 3 Vesicle fuses with endosomelower pH 4 LDL Receptor releases the LDL because of lower pH in the endosome 5 LDL goes to lysosome 6 LDL is degraded into protein and cholesterol 7 LDL receptor is recycled Budding formation of multivesicular body vesicle within a vesicleoccurs in late endosome Budding and Invagination seem like the same thing Budding into cytoplasm or away from cytoplasm Snares Vsnare on vesicle and Tsnare on target form stalkHemifusion outer leafletFusion both leaflets Used to bring two membranes together ClathrinClathrin Triskelions 3 heavy chains and 3 light chainsCreates dome outer surface to drive invaginationClathrin moves things into cytoplasm intracellular space COPI and COPIICoat protein induces bending during invagination inwardClathrin is also working to bend INTO cytosol DynaminDrives fission after invagination needed after the coat proteins bend itPulls the two membranes close together to fuseDynamin and associated proteins bring bilayer together to be pinched off Escort Machinery ESCRTInvolved in multivesicular body important in isolating signallingSeries of proteins involved in bending away from cytosolFunction o Bend membrane away from cytosol o Recruits cargo o Fuses membranes to be pinched Membrane transport machinery regulated by 1 Snares directs vesicle to its target 2 Signalling lipids PIPS specific protein binding 3 Small GTPases turns proteins on and off 4 Signal Sequences on Cargo 5 Membrane Composition Phosphatyl Inositotide PIPInositol sugar headphosphate C1lipidKinase adds P phosphorylatedPhosphatase removes P dephosphorylatedDifferent PIPs bind to different specific proteinsKnow Three Exceptions 1 PI35PPI3P 2 PI5PPI35P 3 PI5PPI
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