Lecture 17 - Cytoskeleton & CM: Motor Proteins

Question 1

def: movement of a cell or organism through the environment, movement of the environment past or through the cell, movement of components in the cell

Answer 1

cell motility

Question 2

def: the shortening of muscle cells, and is a specialized form of motility

Answer 2

cell contractility

Question 3

what are the 2 eukaryotic motility systems?

Answer 3

1. interactions between microtubules and motor proteins kinesics and dyenins
2. interactions between actin microfilaments and members of the myosin motor proteins

Question 4

motor proteins convert chemical energy into __________ _________

Answer 4

mechanical energy

Question 5

how to molecular motors move?

Answer 5

unidirectionally along their cytoskeletal components in a step wise manner

Question 6

what are the 3 categories of molecular motors?

Answer 6

1. kinesins
2. dyneins
3. myosins

Question 7

what do each of the molecular motors use as tracks?

Answer 7

kinesis and dyneins use microtubules and myosin use microfilaments

Question 8

T or F: motors undergo cycles of ATP hydrolysis, release of ADP + Pi, and acquisition of a new ADP molecule

Answer 8

true

Question 9

do motor proteins have momentum?

Answer 9

no, they are subject to tremendous friction

Question 10

are motors processive?

Answer 10

yes they move along a cytoskeletal filament for significant distances

Question 11

traffic toward the (-) ends of microtubules is considered _____________; toward the (+) end is _______________-

Answer 11

inbound and outbound

Question 12

def: movement of vesicles and organelles along microtubules

Answer 12

fast axonemal transport

Question 13

____________ is involved in ATP-dependent transport toward the plus ends (away from the centrosome), called ____________ ________ ____________

Answer 13

Kinesin I, anterograde axonal transport

Question 14

___________ ______________ moves particles in the opposite direction towards the minus end, called __________ ___________ _____________

Answer 14

retrograde axonal transport

Question 15

what is the size of steps that kinesis move along the microtubules in

Answer 15

8 nm

Question 16

what are the 4 parts of a Kinesin I tetramer?

Answer 16

1. a globular head region that attaches to MTs (act as ATP hydrolyzing engine)
2. a neck region (connect head to stalk)
3. a coiled helical stalk region (provide flexibility)
4. a light chain region (attaches kinesis to proteins, organelles, or other cargo)

Question 17

KRP tail regions are ________ ___________-

Answer 17

highly divergent, reflecting cargo diversity

Question 18

def: moves with HIGH processivity toward the minus ends of microtubules

Answer 18

cytoplasmic dyneins

Question 19

does dynein directly interact with cargo?

Answer 19

no it requires an adaptor molecule like dynactin and spectrin

Question 20

def: generate motility in the cilia and flagella

Answer 20

axonemal dyneins

Question 21

T or F: organelles may bind kinesin and dynein simultaneously with motors engaging in a tug of war type battle for the cargo

Answer 21

true

Question 22

def: found in unicellular and multicellular eukaryotes, display an oar-like pattern of beating, generating a force perpendicular to the cilium

Answer 22

cilia

Question 23

_________ cilia move fluid through tracts

Answer 23

motile

Question 24

____ ______ ______ cilia are thought to have sensory functions

Answer 24

non-motile

Question 25

def: move cells through a fluid environment, they are the same diameter as cilia, but usually longer

Answer 25

flagella

Question 26

force generated by flagella is ________ to the flagellum

Answer 26

parallel

Question 27

what is the common structure shared between cilia and flagella

Answer 27

axoneme

Question 28

where do cilium/flagellum emerge from?

Answer 28

basal body and surrounded by an extension of the cell membrane

Question 29

between the axoneme and basal body is a __________ ________ in which the microtubules begin to take on the pattern characteristic of the axoneme

Answer 29

transition zone

Question 30

the axoneme consists of _______ ________ ________ _________ surrounding a ________ _______ _________ __________

Answer 30

nine peripheral microtubule doublets, central pair of single microtubules

Question 31

each microtubule double consists of ?

Answer 31

- 1 complete microtubule - 1 incomplete microtubule

Question 32

the central tubules are enclosed by a _________ connected to the peripheral doublets by radial spokes

Answer 32

sheath

Question 33

__________ ____________ project from the A microtubule as pairs of "arms"

Answer 33

axonemal dyneins

Question 34

what does the assembly and disassembly of cilium and flagellum require?

Answer 34

the transport of material to and form the distal tip

Question 35

def: movement of structural components between the peripheral doublets and the cell membrane

Answer 35

intraflagellar transport

Question 36

def: pulls the IFT trains towards the cilium/flagellum tip

Answer 36

Kinesin-2

Question 37

def: causes microtubule sliding within the axoneme allowing cilia and flagella to bend, there is no change in the overall length of the microtubules

Answer 37

axonemal dynein

Question 38

the stem of each axonemal dynein molecule is tightly anchored to the outer surface of the __ __________

Answer 38

A tubule

Question 39

def: the presence of this prevents the sliding of the doublets past each other

Answer 39

nexin

Question 40

at any given time, what is the status of the axonemal dyneins on either side of the axoneme

Answer 40

one side is active while the other is not

Question 41

where are primary cilia used?

Answer 41

in sensory structures