Cell Bio Section 7 Study Notes PDF[2889].pdf - Cell Biology...

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Cell Biology Section 7 Study Notes Types Of Cytoskeleton = Actin Filaments 2 stranded helical non-covalent polymer of globular (G-actin) actin 5-9 nm in diameter Linear bundles, 2-D & 3-D networks Cell Shape Cell movement & force Actin cytoskeleton is made up of actin & it works as an assembly of actin to make a filament, they do it on ether own & like being apart of a filament kinda like lego It is a narrow filament but it is very important because there is a lot, they have bundles that can be compared to a rope whee each thread is packed together to make one strong formation Muscle movement requires actin meshwork to slide motor portions along to realist in movement Non-covalent polymer, each individual subunit protein is covalent attached of amino a acids but when assembled there non-covalent Types Of Cytoskeleton : Microtubules Cylindrical non-covalent polymer of tubulin Originate from the microtubule organizing centre (MTOC) Cell shape & movement Membrane trafficking & intracellular distribution of organelles They differ because they are made up alpha & beta while actin is not The proteins are covalent amino acids but once they are assembled they are not covalent Hollow interior, its stiff The mitotic spindle uses microtubules They have lost of roles when cells aren't dividing They are important because they provide rigidity & structure but can versatile
Cytoskeletal Functions In 1. Dynamic Processes: Cell motility Phagocytosis Cell Division Cell Contraction Intracellular Transport Cytoskeleton is dynamic & adaptable Cytoskeletal Changes During Cell Division When cells enter cell cycle: 1. Actin Filaments form the contractile ring that splits the cell in cytokineases 2. Microtubules form the mitotic spindle that separates chromosomes during mitosis Microtubules in the acton skeleton go through lots of changes At different times throughout the cells processes it has to be able to take its rigid cytoskeleton & mold it Cytoskeleton Functions In 2. Static processes (Undergo Very Slow Changes: Epithelium tissue Neuronal Networks Nuclear Envelope Epithelium: Stable & Strong Cytoskeleton Network Actin = forms a microvilli that increases surface area of cells & stabilize tight junctions Microtubules = form “transport’ tracks form one end to the other in epithelial cells Intermediate Filaments = stabilizes cell connections celled desmosomes Red = actin Green = microtubules
Cytoskeleton Dynamic, has rapid changes such as phagocytosis Slow, lasting structures such as epithelium Same cytoskeleton in both cases due to its dynamic nature Some cells don't do much but they need a rigid framework to maintain the structure The cytoskeleton is like a support beam in the epithelial cells for the intestinal barrier Microtubules form post-like structures to maintain rigidity Cytoskeletal Filaments Are Built From Monomer Protein Subunits How can the city be both dynamic & static? cells are able to build new actin & take the actin apart

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