Molecular Cell Lodish 7th EditionExam # 3 Study Guide Membranes are fluid and can move from one place to another remember microtubules are tracks for vesicle movement. TRUEWhat are lysosomes? Specialized vesicles that carry acid hydrolases**Remember the importance of V-snares and T-snaresV-SNARES– Crucial to eventual fusion of the vesicle with the target membrane– Shortly after formation of vesicle is completed, GTP is hydrolyzed and coat is shed– The v-SNARE is exposed after the protein coat is shed• Target membrane contains T-SNARES• Association between v-snares and t-snares allow the vesicle to fuse to the organelleHow does a vesicle “know” where to go? SNARE molecules work likepuzzle pieces.vSNARE = vesicle snaretSNARE = target snareThey must be a match in order to get fusion of the vesicle.What is Endocytosis? Invagination of a small region of the plasma membrane to form vesiclesReceptor-Mediated Endocytosis involves a specific receptor on the cell surface which binds to an extracellular macromolecular ligand. TRUELipoproteins contain a proteins Apo lipoprotein B. TRUEMOTOR molecules physically move by a conformational change that occurs when ATP binds and or is hydrolyzed. TRUE Actin exists as globular monomer called F-actin. FALSE the correct answer is G-actinFilamentous polymer called F-actin. TRUEWhat is myosin? Is a motor protein that is associated with actin.Know the roles and different types of myosin.Different types of myosin are associated with different activities• All myosin’s convert ATP hydrolysis into work• Myosin II– many molecules pull together on actin filaments • Myosin V– binds to vesicular cargo to transport it along actin filamentsThe unit of contraction is called the SARCOMERE. TRUEWhat is Protein targeting and sorting? Delivery of newly synthesized protein to their proper cellular destinationsCytoplasmic proteins can be localized to the nucleus when they are fused to a nuclear localization signal. TRUEKEY TERMS:- Immunoprecipitation (IP) is the technique of precipitating a protein out of solution using an antibody that specifically binds to that particular protein.- Co-immunoprecipitation (Co-IP) is a popular technique to identify physiologically relevant protein-protein interactions by using target protein-specific antibodies to indirectly capture proteins that are bound to a specific target protein.Functions of Membranes:- provide a barrier- concentrate solutes- provide structure**REMEMBER:1. Hydrophobic tails aggregate together to form a bilayer2. Hydrophilic heads face both the hydrophilic inside of cell and the hydrophilic outside of the cellThree classes of membrane lipids are:1. phosphoglycerides,2. sphingolipids, 3. sterols4.All phosphoglycerides are phospholipids. TRUECholesterol can make membranes more or less fluid and this helps when the outsidetemperature changes. TRUECholesterol is important in maintaining the appropriate fluidity of natural membranes. TRUEKEY NOTES TO REMEMBER:All Transmembrane Proteins and Glycolipids Are Asymmetrically Oriented in the Bilayer• Every type of transmembrane protein has a specific orientation, known as its topology, with respect to the membrane faces• No flip-flop across a membrane• Both glycoproteins and glycolipids are always located in the exoplasmic leaflet with the carbohydrate chain protruding from the membrane surface.• interact with components of the extracellular matrix as well as lectins (proteins that bind specific sugars), growth factors, and antibodies.GOOD