4. Motor proteins & intermediate filaments

Question 1

name the 2 key microtubule motor proteins

Answer 1

kinesin and dynein

Question 2

what is anterograde transport, which motor protein does this

Answer 2

cargo moves towards + end of the microtubule

kinesin

Question 3

what is retrograde transport, which motor protein does this

Answer 3

cargo moves towards - end of the microtubule

dynein

Question 4

describe the structure of kinesin

Answer 4

• head domain has ATP binding site + microtubule binding site
• neck region is flexible and responsible for the direction of movement
• motor domain generates movement

Question 5

what is the structure of kinesin 1

Answer 5

has 2 heads which bind to microtubule sites and step forwards along the microtubles

Question 6

what is the speed of kinesin

Answer 6

600 nm

Question 7

where is kinesin 5 found

Answer 7

in mitotic spindle

Question 8

what is the role of kinesin 13

Answer 8

assists in disassembly of microtubules at + end and - end

Question 9

how are dyneins linked to their cargo

Answer 9

linked by large complexes of dynactin

Question 10

what is a similarity between dynein and kinesin

Answer 10

both has ATPase domains and microtubule binding domains

Question 11

what does cilia and flagella movement depend on

Answer 11

Bending of the axoneme generated by motor proteins

Question 12

why does the axoneme bend rather than slide past

Answer 12

due to restrictions imposed by cross-linking protein nexin in the axoneme.

Question 13

what are the 3 types of microtubules in spindle fibers

Answer 13

kinetochore microtubules, polar microtubules, astral microtubules

Question 14

what do kinetochore microtubules do

Answer 14

connect chromosomes to the spindle poles

Question 15

what do polar microtubles do

Answer 15

overlap and are involved in holding the poles together and regulating pole-pole distance

Question 16

what do astral microtubules do

Answer 16

help position the spindle and determine the plane of cytokinesis

Question 17

what proteins form intermediate filaments

Answer 17

keratin or lamin

Question 18

what is the role of intermediate filaments

Answer 18

provide mechanical support for the nuclear membrane or for cell adhesion

Question 19

what class of intermediate filaments are involved in tissue strength

Answer 19

class 1 and 2

Question 20

what class of intermediate fibre is involved in axon organisation

Answer 20

class 4

Question 21

what is the structure of intemediate filaments

Answer 21

alpha helical rod structure, that overlap producing a rope-like structure

assembled into an antiparallel tetramer

Question 22

what is the intermediate fibre tetramer assembled into

Answer 22

assembled into protofilaments, twisted into a robe like structure called a protofibril

Question 23

what is the role of intemediate filament associated proteins (IFAP)

Answer 23

connect adjacent IFs together, interact with skeletal components

Question 24

give an example of IFAPs

Answer 24

plakins

Question 25

what disease is caused by mutations to IF genes

Answer 25

epidermolysis bulls simplex

Question 26

what is kartenegers syndrome

Answer 26

hereditary defects in ciliary dynein, results in infertility (non-motile sperm) and paralysed cilia