Unit 6 Flashcards
Cytoskeleton filaments from smallest to largest
microfilaments, intermediate filaments, microtubules
Intermediate filaments are only in ___ cells
Animal
Function of intermediate filaments
Function to absorb mechanical strain within cells and tissues
Intermediate filaments structure
Long twisting strands on fibrous proteins that form coiled coils
IF polarity
Non polar as monomers are orientated in both directions
Cytoplasmic branch of IF includes
Keratin filaments, vimentin, neurofilaments
Nuclear branch of IF invoudes
Nuclear lamina
Actin filaments and microtubules are called polar because
The two ends of the polymer are different from one another
Role of desosomes in IF
Join adjacent IF epithelial cells
Hemidesomes role in IF
Anchor IFs to basal lamina
What subunit is able to hydrolyze GTP to GDP
Beta
How would a mutation in IF affect the cells
Restrict its ability to resist tension/ stretching forces
Active tubulin is bound to
GTP that readily incorporates into growing plus size end of microtubules
Inactive tubulin is bound to
GDP. After being incorporated into microtubule B tubulin hydrolyzes GTP to GDP
GTP tubulin has a ___ conformation whereas GDP tubulin is _____ leading to _____
Straight, curved, dynamic instability
Rate of polymerization is dependent on
Location
What is meant by critical concentration
Min concentration of monomers required for polymer formation to begin, the conc maintained at equilibrium, and conc of monomers where MT switches from shrink to grow
What is a MTOC
Sites within a cell where nucleation begins
MTOC role
Concentrate y tubulin protein, which is essential for starting microtubule polymerization
Examples of MTOC
Centrosome, basal body, spindle pole, plant cell MTOCS
How can microtubules be stabilized
MAPS- microtubule associated proteins that organize cytoskeleton and maintain cell shape. Bind different MT together and cap them
Dynein and kinesin are both
Motor proteins
Kinesin moves towards
Plus end of MT and transports vesicles, organelles, and proteins. Ex. Axonal transport
Dynein moves towards
The minus end carrying endosomes, lysosomes, and Golgi derive end vesicles
G actin characteristics
Globular form, soluble in cytoplasm, joins together to form, F actin
Lamelliopdia
Thin flat projections that extend from leading edge of migrating cells that have a actin rich membrane
What controls the behavior of F actin
ABPS - acting binding proteins
What does the arp 2/3 complex do
Initiates new actin filaments by creating branches at a 70 degree angle
What do integrins do for lamelliopdiums
Helps anchor internal F actin to EC matrix
Simple muscle contraction myosin mechanism
ADP bound myosin head is attached to actin, ADP converted to ATP and myosin head slides along filament, power stroke happens as myosin head binds new actin site to og confirmation dragging actin along
How does rigor mortis
Occurs when contraction cycle halts and no atp is present to release myosin head, and muscle stays contracted
Taxol effect on kinesin on Dynein
Stabilizes microtubule and prevents depolymerization so the mt become overly stable and transport efficiency may decrease
Colchione effect on kinesin and Dynein
Destabilizes mt and bind to tubulin to prevent polymerization, so mt don’t have anywhere to move on and transport stops
Which end of mt is attached to chromosomes during anaphase
Plus end
Structure of anoxemes
9 + 2 arrangement ( ring with 9 pairs and 2 single ones in middle
What type of interactions make up actin filaments
Non covalent
G actin and f actin interactions
Non covalent
