Biology 2382B Lecture Notes - Lecture 1: Pericentriolar Material, Tubulin, Microtubule
7 May 2019
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Network of protein filaments that extend throughout cytoplasm: microfilament (7-9nm): actin, most thick, microtubules (25nm): ab-tubulin dimer, largest, intermediate filament (10nm): various, depends on tissue/cells. Microtubules: polymer of a b tubulin (exist together-difficult to separate, ab dimer is a basic subunit of microtubules. Bind as protofilament alpha end (-) and beta (+), dimers have polarity: alpha bind gtp and beta gdp (hydrolysis) Seam: alpha unit meets beta in adjacent one. Dimeric tubulin subunit: very stable, alpha binds permanently to gtp, b hydrolyze gtp to be bound gtp or gdp. Arrangement of mt protofilaments: need 13 protofilament to make microtubule, singlet (cytoplasm): dynamic, dissemble easily (13 form, doublet (cilia, flagella)/triplet (basal body, centrioles) 2 types: cytoplasmic: dynamic, disassemble easily, axonemal (cilia, flag): stable, shift materials through layer. Organization: cell use microtubule organizer centre to initiate assembly of microtubule, + end extends away from centre. Centrosomes: major mtoc in animal cells, contain centrioles (not found in plants) centrosomes have 2 centrioles.
