Cytoskeleton Motors

Question 1

Cytoskeleton motors like myosins and kinesins utilize [blank] to generate force and facilitate movement.

Answer 1

ATP hydrolysis

Question 2

cystokeleltal motors like myosin and kinesin undergo 4 main cyclic mechanisms:

Answer 2

• bind to filament (MT or AF)
• Conformational change via ATP hydrolysis
• Filament release
• Relaxing and Rebinding again

Question 3

why are the 4 main cylic mechanisms important (binding, conformational, release, rebind)

Answer 3

to generate proper directional movement and force

Question 4

2 types of motors

Answer 4

processive and non-processive

Question 5

2 examples of processive motors:

Answer 5

kinesin and myosin XI

Question 6

what does processive motors like kinesin and myosin XI do? what does it mean to be a processive motor?

Answer 6

can complete multiple ATP hydrolysis cycles while remaining bound to the filament, which ensures continuous cargo movement without detachment.

Question 7

example of non processive motors

Answer 7

myosin II

Question 8

What do the non processive myosin II motors do to be non processive

Answer 8

Unlike myosin XI and kinesin that dont detach from the filament, myosin II (non processive) release from the filament during ATP hydrolysis cycles.

It’s okay though, since multiple myosin molecules work together, they still maintain the structural integrity and movement of the filament.

Question 9

Processive motors function like [blank] (maintaining grip), while non-processive motors act like rowers [blank]

Answer 9

porters, release in coordinated fashion

Question 10

two main classes of plant myosins

Answer 10

myosin VIII and myosin XI (processive motor)

Question 11

feature of myosin VIII

Answer 11

unique to plants, involved in cell to cell junctions

Question 12

features of myosin XI

Answer 12

• Analogous to Myosin V in ANIMALS
• fastest myosin, with 35 nm step lengths and key roles in cytoplasmic streaming.

Question 13

What is cytoplasmic streaming

Answer 13

bulk flow of cytoplasm that aids in providing nutrients/ organelle movment

very important in large plants

Question 14

2 ways of actin-myosin transport (how actin is transported via myosin)

Answer 14

root hair vesicle transport and golgi body movement transport

Question 15

what happens in root hair vesicle transport

Answer 15

Myosin delivers vesicles along AFs, supports growth in root hair cells

Question 16

What happens golgi body movement transport

Answer 16

myosin motor (myosin XI) facilitates golgi body movement along AFs, aids in growth and development

Question 17

golgi are [blank] structures while ER form [blank] networks

Answer 17

punctate, reticulate

Question 18

are they dyneins in plants

Answer 18

no

Question 19

Arabidopsis has [blank] kinesin genes, more than in [blank] (what species). This diversity compensates for the absence of dyneins in plants, giving kinesins greater functional roles.

Answer 19

61, humans

Question 20

how are plant kinesins (no dyneins) involved in mitotic roles

Answer 20

-spindle formation
-binding to chromosomes
-interacting with phragmoplast and pre-prophase band.

Question 21

how do plant kinesins function beyond transport

Answer 21

• help bundle microtubules and promote microtubule catastrophe (disassembly at the ends).

Question 22

Myosin XI’s 35 nm steps are precise and essential for processivity, allowing efficient [blank]

Answer 22

cytoplasmic streaming

Question 23

Kinesin 1 Stroke: This kinesin motor moves in a [blank], each step driven by ATP hydrolysis. Does it detach from the filament?

Answer 23

hand over hand mechanism, stays attached to MTs

Question 24

Specific kinesins act as minus-end directed motors that promote microtubule depolymerization, which one?

Answer 24

kinesin 13

Question 25

which myosin motor is important in cytoplasmic streaming

Answer 25

myosin XI

Question 26

why is it important to also depolymerize and promote MT dissasembly

Answer 26

spindle assembly and chromosome segregation during mitosis

Question 27

what is the muscle myosin

Answer 27

myosin II

Question 28

BOTH myosin and kinesin have a …. (domains, 2 of them)

Answer 28

head motor, interacting tail domain