Discussion of all aspects of cellular structure, physiology and communication.
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Eukaryotic cells contain a supportive meshwork of fine fibers collectively called the cytoskeleton.The fibers of the cytoskeleton extend throughout the cytoplasm.Three main fibers make up the cytoskeleton:microfilaments,the thinnest type of fiber are solid helical rods composed of a globular protien called actin.A microfilament consists of a double chain of actin molecules.Actin microfilaments can help cells change shape and move by assembling(adding subunits) at one end while disassembling (losing subunits) at the other.Actin microfilaments often interact withother kinds of protien to make cells contract. Intermediate filaments are made of fibrous protiens rather than globular ones and have a ropelike structure.They serve mainly as reinforcing rods for bearing tension but also help anchor certain organelles.Such as the nuecleus often held in place by a cage of intermediate filaments. Microtublules the thickest of fibers are straight hollow tubes composed of globular protiens called tublulins.Microtubules elongated by adding subunits consisting of tubulin pairs.They are readily disassembled in a reverse manner,and the tubulin subunits can then be reused in another microtubule that provide rigidity in one area may disassemble and reassemble elsewhere in the cell.Other important functions are to provide anchorage for organelles and to act as tracks along which organelles can move within the cytoplasm.For example a lysosome might move along a microtubule to reach a food vacuole.Microtubules also guide the movement of chromosomes when cells divide, and they are the basis of ciliary and flagellar movement.
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