Ch. 14: Cellular movement: motility and contractility

Micotubule based moement inside cells: ____ and ___

kinesins, dyneins

microtubule associated ___ ___ ___ and ____ walk along the MTs and provide the force needed for movement

motor proteins- kinesins, dyneins

_____ are a large famiy of proteins whereas there are relatively few dyneins

Kinesins

Kinesins move cargo in what direction on microtubules

negative to positive

One major function of kinesins is ___ ____ ___

moving intracellular cargo

Kinesins consist of two dimerized ___ ___ and two ___ ___

heavy chains, light chains

MISSINGGGGG

____

How kinesin mov cargo along microtubules-

• ___ ___ looks like walking with the two globular head domains taking turns as the front foot

• kinesin act as highly processive _____ traveling great distances along MTs

• Movement is coupled to the _____ of ___

• kinesin movement

• motors

• hydrolysis of ATP

dyneins move from

plus to minus end

dyneins are found in ____ and the ___

axonemes and the cytosol

Dyneins fall into two classes:

cytoplasmic and axonemal

cytoplasmic dyneins move forward to the ___ end of MTs

minus

The _____ complex serves as an adapter between dyneins and their cargo

dynactin

The ____ domain is an ATPase. it is responsible for the ___ ___ that moves dyneins along the MT

AAA+, power stroke

__ ___ direct vesicle transport and shape the endomembrane system

Microtubule motors

______ anchor a polarized array of MT with the plus end at the cell periphery. MT motors move cargo along this network

Centrosomes

MT motors can shape the endomembrane by moving the ___ along the MT and by assembling and maintaining the ____ apparatus

ER, golgi

Microtubule based cell motility: ___ and ___

cilia, flagella

____ occur in large numbers on the surface of ciliated cells (oarlike pattern of beating)

cilia

_____ are limited to one or a few per cell (propagated bending motion)

Flagella

Cilia and flagella consist of an ___ connected to a ___ body

axoneme, basal

the nine ___ ___ of the axoneme are connected laterally to one another and radially to the ___ __ of single MTs

outer doublets, central pair

Each A tubule has a set of ____ that project from each of the outer doublets these consist of ____ ___

sidearms, axonemal dynein

crosslinks and spokes are responsible for ____

bending

_____ ____ is invovled in the sliding of MTs against each other which bend the axoneme

axonemal dynein

____ ___ provide the driving force for axonemal bending

dynein arms

microfilament based movement inside cells: ___

myosins

atp dependent motors the large superfamily called __ interact with and exert force on actin microfilaments

myosins

many myosins move toward the ___ ___ of MFs

plus ends

Myosin functions:

muscle contraction, cell movement, endocytosis, and vesicle transportation

Myosin 2 and classic kinesin are efficient motor proteins that share these similarities:

• both have ___ ___ that walk along a protein filament

• both use ____ ___ to change their shape

• the ____ exerted are similar

• globular domains

• ATP Hydrolysis

• forces

Myosin 2 and classic kinesin differences:

• myosin 2 molecules move ___ distances but operate in ___ arrays

• kinesins operate ____ or in ___ numbers to transport vesicles over large differences

• short, large

• alone, small

myosin goes to

plus end/ toward z line

_____ ___ are responsible for voluntary movement

skeletal muscles

skeletal muscles cells contain ____ filaments (actin) and ___ filaments (myosin)

thin, thick

study

study

Muscle contraction is due to ___ filaments sliding past ___ filaments with no change in length either

thin, thick

The mechanism of ___ ___ is a six step cycle (look at the slide)

muscle contraction

The regulation of muscle contraction depends on ____

calcium

The regulatory proteins ___ and ____ regulate the availability of myosin binding sites on actin filaments in a ___ dependent manner

tropomyosin, troponin, calcium

smooth muscle is more similar to nonmuscle cells than to ___ muscle

skeletal

smooth muscle have ___ bodies, actin and myosin filaments are anchored at both ends to the dense bodies

dense

smooth muscle is responsible for ____ contractions

involuntary

The resulting ____ ___ complex binds to myosin light chain kinase activating it and triggering myosin light chain phosphorylation

calcium calmodulin

____ ___ ____ ___ activates the myosin so that it can interact with actin filaments to undergo the cross bridge cycle

myosin light chain phosphorylation

Microfilament based motility in nonmusle cells:

• extension of a ____

• attachment to ____

• generation of ____

• protrusion

• substrate

• tension

Microfilament based motility in nonmusle cells:

____ ____ : an actomyosin dependent movement of cytoplasm in the plant cell

ex: chemotaxis, amoeboid movement, cytokinesis, and some vesicle movement

cytoplasmic streaming