Cytoskeleton And Motility

Dynamic intracellular polymer network providing shape, polarity, transport, division. Three systems: actin (7 nm), intermediate filaments…

Double-helical polar polymer of G-actin monomers (~42 kDa). ATP-actin adds at barbed end; ADP-actin dissociates at pointed end —…

Hollow tube (25 nm OD) of 13 α/β-tubulin protofilaments. Nucleated at γ-TuRC (centrosome, basal body). GTP-cap drives dynamic instability;…

Mitchison-Kirschner 1984: microtubules stochastically switch between growth (rescue) and shrinkage (catastrophe) at plus ends. GTP-cap…

Mechanically resilient (tensile-stress bearing) 10 nm fibres of tissue-specific proteins: keratin (epithelia), vimentin (mesenchyme),…

Actin-based ATPase motor family (>35 classes in humans). Myosin II drives muscle contraction + cytokinesis; myosin V/VI do organelle…

Plus-end-directed microtubule motor (mostly). ~45 human kinesins (KIF1-KIF27). Two heads walk hand-over-hand with 8 nm step per ATP,…

Minus-end-directed microtubule motor. Cytoplasmic dynein does organelle transport + spindle positioning; axonemal dynein powers…

Protrusion (actin polymerisation) → adhesion (integrins) → contraction (actomyosin) → retraction. Arp2/3 drives lamellipodia, formins drive…

Bipolar microtubule structure driving chromosome segregation. Kinetochore-MT attachment, spindle checkpoints, anaphase A (MT shortening)…