CMB1004/L04 Cytoskeleton

Question 1

Name the 4 cytoskeletal filaments.

Answer 1

Intermediate filaments
Microtubules
Actin
Spectrin

Question 2

Give 3 functions of the cytoskeleton.

Answer 2

Organisation
Cell shape and movement
Positioning of organelles
Directs intracellular transport

Question 3

Where are intermediate filaments found? (2)

Answer 3

Cytoplasm
Nucleus

Question 4

What is the function of intermediate filaments? (2)

Answer 4

Provide mechanical strength
Prevent overstretching

Question 5

What is the function of microtubules? (3)

Answer 5

Move chromosomes in cell division
Intracellular transport
Drive cilia and flagella

Question 6

What is the function of actin filaments? (2)

Answer 6

Maintain cell shape
Surface movement

Question 7

What is the diameter of intermediate filaments?

Answer 7

10nm

Question 8

Describe the structure of intermediate filaments.

Answer 8

A-helical coil

Question 9

What is the assembly and disassembly of intermediate filaments regulated by?

Answer 9

Phosphorylation

Question 10

How many tetramers associate to form an intermediate filament?

Answer 10

8 (16 dimers)

Question 11

What groups are on the end of intermediate filaments?

Answer 11

-COOH and -NH2

Question 12

What kind of intermediate filaments are in the nucleus?

Answer 12

Lamins

Question 13

What is the function of nuclear lamins? (2)

Answer 13

Structural support
Anchorage site for chromosomes and nuclear pores

Question 13

Name the 3 cytoplasmic intermediate filaments.

Answer 13

Keratins
Vimentin and related
Neurofilaments

Question 14

Name the 3 nuclear lamins.

Answer 14

LMNA, LMNB, LMNC

Question 15

What causes breakdown of nuclear lamins during mitosis?

Answer 15

Phosphorylation

Question 16

What is the primary purpose of neurofilaments?

Answer 16

Structural support

Question 17

How are intermediate filaments indirectly connected to neighbour epithelial cells?

Answer 17

Desmosomes

Question 18

Why can the orientation of intermediate filaments not be determined?

Answer 18

Dimers align with ends facing opposite ends

Question 19

What is the diameter of microtubules?

Answer 19

25nm

Question 20

What are the globular monomers of microtubules?

Answer 20

Tubulin

Question 21

Where do microtubules emerge from in cytoplasm?

Answer 21

Organising centres

Question 22

What are cytoplasmic microtubules called?

Answer 22

Centrosomes

Question 23

What are mitotic spindle microtubules called?

Answer 23

Spindle poles

Question 24

What are cilia/flagella microtubules called?

Answer 24

Basal bodies

Question 25

How many protofilaments are in a microtubule?

Answer 25

13

Question 26

What energy source is used to form microtubules?

Answer 26

GTP

Question 27

Which end of a microtubule is 1) positive and 2) negative?

Answer 27

1) Beta - positive 2) Alpha - negative

Question 28

What does the polarity of microtubules determine?

Answer 28

Which way organelles move

Question 29

What are the 2 microtubule motor proteins?

Answer 29

Kinesins and dyenins

Question 30

What does the globular head of kinesins and dyenins bind?

Answer 30

ATP + microtubules

Question 31

Which direction does kinesin move in?

Answer 31

Towards plus end

Question 32

Which direction does dyenin move in?

Answer 32

Towards minus end

Question 33

Which motor protein drives cilia and flagella?

Answer 33

Dyenins

Question 34

What microtubule structure do motile cilia have?

Answer 34

9+2

Question 35

What protein do microvilli contain?

Answer 35

Actin

Question 36

What is the function of microvilli?

Answer 36

Increase surface area for absorption

Question 37

What is the diameter of actin filaments?

Answer 37

6-8nm

Question 38

What is the function of actin filaments? (2)

Answer 38

Cell motility + contraction Adhesion + mechanosensing

Question 39

Which monomers are added to each end in formation of actin filaments?

Answer 39

G-actin

Question 40

How is actin filament assembly and organisation regulated?

Answer 40

Actin-binding proteins

Question 41

What is the actin filament motor protein?

Answer 41

Myosin

Question 42

What part of myosin binds to actin filaments?

Answer 42

Myosin head

Question 43

What is the difference between myosin I and II?

Answer 43

Myosin I has 1 head Myosin II has 2 heads

Question 44

What do myosin tails bind to?

Answer 44

Plasma membranes, vesicles, other myosin molecules

Question 45

What drives muscle contraction?

Answer 45

Sliding thick myosin filament

Question 46

What links membranes to motor proteins and all major filament systems?

Answer 46

Spectrin