BIOL 1090 Lecture Notes - Lecture 11: Hemicellulose, Microtubule, Collagen
12 Apr 2017
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Document Summary
A dynamic network of protein filaments that forms the cellular scaffolding as well as transport system for organelles and vesicles. Intermediate filaments fibrous, various proteins diameter 10-12 nm. Microfilaments solid, thin, branches, actin polymenrs diameter 8 nm. Functions of the cytoskeleton slide 3: structure and support. Intracellular transport: contractility and motility, spatial organization. Polymer of proteins a-tubulin and b-tubulin a/b heterodimers form long protofilaments. Mts have fast-growing plus +" end and slow-growing minus +" end. Structural polarity is important for mt growth/shrinkage and direction ofmovement of material along mt. In vivo, this leads to rapid turnover of most mts within cell (half-life is minutes) Shrinkage can occur very rapidly at the plus" end (termed catastrophe") Mtoc = central site of mt assembly. The centrosome is a major mtoc in animal cells. Formation of mts is regulated/controlled by microtubule-associated proteins (maps) Mediate interactions with other cellular structures (e. g. vesicles/ organelles) The bumps at the surface of microtubules are maps.
