Atomic Structure of Tubulin.

(Ribbon and Space Filling Models)

Molecular Structure of a Nucleoside Triphosphate(ATP or GTP)

TEM of Self Assembled MTs and MTs Assembled on a Centrosome “template”

Microtubules and Motors: MT polymer ratchets and motor proteins.

F ~ 1-10pN

F ~1-50pN

Filament Assembly and Force Production.

Flux. (Margolis and Wilson, 1978; Mitchison, 1989).

Dynamic Instability.(Mitchison and Kirschner, 1984).

Microtubule Polymer Dynamics

GTP hydrolysis and Dynamic Instability at Steady State.

Microtubule Dynamics in Anaphase A

Metaphase

Anaphase A

Anaphase B

Kinetochore motility - Pacman versus poleward flux.

Mechanism of Chromosome Movement.

MT dynamics in Anaphase B

Metaphase

Anaphase A

Anaphase B

Anaphase B Spindle Elongation

1. A motor-dependent sliding filament mechanism generates force to push the poles apart.

2. Poleward flux acts as a regulatory switch.