Lecture 9

provides mechanical strength and help cell resist shear stress • keratin • neuro filaments. helps hold axons in neurons

aid in positioning of internal organelles and intracellular transport

help in shaping the cell and in whole cell locomotion

are very dynamic. constantly changing.

from one z disk to another

• Made of small protein subunits • Subunits are held together by weak non-covalent interactions • Accessory proteins interact with filaments to allow for highly organized internal structures

• May be multiple long strings of subunits joined end to end and associate laterally • Twist around one another - makes them really stable and strong

2 13 4

• has small globular subunits - have longer subunits making them a little stronger

• not about interactions w aqueous envir - polar (different ends) and non polar (same ends)

• they are not charge • things are going to be added added/subtracted faster on plus end • minus end can add but slower

• alpha tubulin and beta tubulin - form dimers to make protofilament

GTP (just changes shape). alpha tubulin doesnt hydrolyze, but beta tubulin hydrolyzes GDP and has different shape.

isoforms

is not an organelle bc it has no nucleus. non membrane bound

drug that inhibits formation of microtubule filaments. binds subunits and prevents polymerization

highly specific proteins. They have shape of a Y. has disulfide bonds (formed by cysteine). They are tertiary structure. Antibodies stick on one end, on flurescent.

• polar • globular monomer called g-actin • g actin binds ATP

on the outer part of microtubule

they are not organized. theyre everywhere.

going out. toward periphery

going in. toward center

outer portion. allows for cell movement.

ropelike structures that provide strength and flexibility. important for motility and structure; highly dynamic structures