BCOR 103 1st Edition Lecture 8 Outline of Last Lecture I. The Chemiosmotic Theory of ATP ProductionII. ATP SynthaseIII. Professor answered questions for exam rest of class, chloroplasts will not be included on the exam.Outline of Current Lecture I. The CytoskeletonII. Cytoskeletal StructuresIII. Filament AssemblyIV. Dynamic InstabilityCurrent LectureThe cytoskeleton is the architectural material of the cell. The key activities that it is associated with are: cell shape, positioning organelles, macromolecular metabolism, a track for the transport of materials within the cell, cell movement, and transduction between cells. Cytoskeletal StructuresFilament System Major Protein Subunit Structure Diameter Major Function(s)Microtubules α , β- Tubulins Hollow Tube, 22nmCell Polarity,Cell Division,Intracellular TransportIntermediateFilamentsVariable FibrousProtein Rope-like Fiber, 10nmBasic Support,Cell Shape, ResistStressMicrofilaments ActinGlobular ProteinChain 6nmCell Elasticity,Cell MotilityThick Filaments Myosin (Muscle-like)Rough Bipolar Fiber15nm ContractilityThese 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.Intermediate Filament Proteins assemble in a building-block like sequence. Starting with one α-helical region, then a coiled dimer of the two, then a combined staggered dimer, the association of eight tetramers, which come together to make up filaments. This building-block process produces a stress resistant filament. There are N and C terminal domains that project to the surface to provide binding sites for other components. Without filaments, a layer of cells would not stretch and remain intact, they would rupture.Dynamic Instability refers to the growth and collapse of microtubules. A growing microtubule lengthens when GTP binds to tubulin molecules. The microtubule can collapse when GTP hydrolysis occurs, and the microtubule peels itself away. Additionally, some microtubules become stable when they meet a capping protein at the cell membrane. Others do not get capped and so they grow and shrink over and
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