BIOSC 150 1nd Edition Lecture 9 Outline of Last Lecture I Membrane and Disease Outline of Current Lecture 1 Subcellular structures A Actin Cystoskeleton 2 Disease Current Lecture Three types of filamentous proteins comprising the cytoskeleton 1 Microfilaments actin small diameter polymer made of actin monomers 2 Intermediate Filaments intermediate diameter polymer made of various proteins depending on the cell type 3 Microtubules large diameter polymer made of the proteins alpha and beta tubulin Cytoskeletal filaments are long chains made up of repeating protein subunits monomers Microfilaments A subunit of actin Chain wounded to form a double helix long strands Two forms of actin 1 Globular 2 Filamentous are constantly interconverting Requires energy in the form of ATP Composed of non covalent bonds due to the fact that they require less energy to break Actin filaments are asymmetric have polarity therefore making the whole polymer polar Actin can form different types of bundles that help to shape the cell these bundles include contractile bundles gel like networks and tight parallel bundles Filapodium highly dynamic environmental sensors 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 Actin polymerizes under the plasma membrane and therefore causes it to move in and out Apical Surface top surface of a cell Lamellipodia push out membrane for movement polymerizing actin into gel network in order to push the membrane out Myosins are motor proteins that use the energy of ATP hydrolysis to travel along actin Myosins have the ability to carry cargo Mutations in myosin 5 disrupt melanosome transport causes of albinism Myosin can move organelles and cytoplasm in plants Actin filaments can form anti parallel bundles that along with myosin allow contraction muscle cells and others Filamentous myosin effects contraction of anti parallel actin filaments
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