Cell Motility and the Cytoskeleton - Exam Questions

Question 1

Actin..:

a. is made up of subunits of F-actin
b. can be polymerised to form microtubules
c. is made up of two types of subunit: F-actin and G-actin
d. is a double helix
e. is a triple helix

Answer 1

d. Actin is a double helix

Question 2

What is the diameter of an actin filament?

Answer 2

7nm

Question 3

Polymerisation of actin filaments:

a. occurs more quickly at the minus end of the actin
b. occurs when the subunit is bound to ADP
c. is irreversible
d. can only occur at the plus end of actin
e. requires ATP to be bound to the actin subunit

Answer 3

e. Polymerisation of actin filaments requires ATP to be bound to the actin subunit.

Question 4

The actin binding protein transgelin is…

Answer 4

…a cross-linking protein

Question 5

Give an example of an actin-sequestering protein.

Answer 5

Profilin

Question 6

The following is not a type of intermediate filament:

a. keratin
b. vimentin
c. neurofilamin
d. spectrin
e. glial fibrillary acidic protein

Answer 6

d. spectrin is not a type of intermediate filament.

Question 7

How are intermediate filaments formed?

Answer 7

From tetramers linked in a staggered formation.

Question 8

What are intermediate filaments joined to actin and microtubules by?

Answer 8

Plectin

Question 9

Axons lacking intermediate filaments are..

Answer 9

..reduced in diameter

Question 10

What is the microtubule diameter?

Answer 10

25nm

Question 11

The subunits that polymerise to form a microtubule are:

a. alpha, beta and gamma tubulin, jointed to forma hererotrimer
b. gamma tubulin only
c. alpha tubulin only
d. G-tubulin bound to G-actin
e. alpha and beta tubulin

Answer 11

e. The subunits that polymerise to form a microtubule are alpha and beta tubulin

Question 12

What are microvilli supported by?

Answer 12

Bundles of actin filaments

Question 13

Microtubules maintain the organisation of the..?

Answer 13

Endoplasmic reticulum

Question 14

Cell movement can occur when:

a. intermediate filaments polymerise and depolymerise rapidly
b. actin filaments polymerise and depolymerise rapidly
c. microtubules are sent out from the centrosome
d. the cytoskeleton breaks down
e. protrusion filaments form within the cell

Answer 14

b. Cell movement can occur when actin filaments polymerise and depolymerise rapidly.

Question 15

What are lamellipodia?

Answer 15

Exploratory processes formed by actin and integrins

Question 16

How do actin and myosin form movement?

Answer 16

Myosin pulls on actin

Question 17

What are cilia movements associated with?

Answer 17

Microtubules and dynein

Question 18

What do kinesin and dynein do?

Answer 18

Move in opposite directions along microtubules; kinesin +, dynein -

Question 19

What is the rate of vesicle movement when attached to kinesin or dynein?

Answer 19

1celsiusm per day

Question 20

What is the mechanism of colchicine in preventing cell division for?

Answer 20

To destabilise microtubules

Question 21

Give an example of an intermediate filament disease.

Answer 21

Epidermolysis bullosa symplex

Question 22

How does lysteria bacteria spread between cells?

Answer 22

Causing actin to polymerise behind the bacteria.