Cytoskeleton W2

Question 1

What are the three classes of filaments

Answer 1

Microfilaments
Intermediate filaments
Micro tumbles

Question 2

What are the roles of filaments in the cytoskeleton (4)

Answer 2

• Structure and support/mechanical stability
• intracellular transport
• cellular motility
• spatial organisation

Question 3

Microfilament diameter

Answer 3

7nm

Question 4

Intermediate filament diameter

Answer 4

10nm

Question 5

Microtubules diameter

Answer 5

25 nm

Question 6

What are microfilaments made of

Answer 6

Actin subunits arranged in a long spiral chain

Question 7

Where are microfilaments found

Answer 7

Beneath cell cortex

Question 8

2 properties of microfilaments

Answer 8

Dynamic

Have a plus minus end

Question 9

Why are microfilaments dynamic

Answer 9

They rapidly polymerise and depolymerise

They grow and shrink via addition or removal of actin subunits

Question 10

What happens at the plus end of a microfilament

Answer 10

Faster addition/removal of actin subunits

Question 11

What happens at the minus end of a microfilament

Answer 11

Slower addition/removal of actin subunits

Question 12

Microfilament roles in a cell(2)

Answer 12

Acts as a track for myosin motor motility

Enables cells to hold and move specialised shapes

Question 13

Examples of microfilaments role in shape change and movement of a cell (2)

Answer 13

Involved in membrane pinching process in cell division

Formation of pseudopodia

Question 14

What is pseudopodia

Answer 14

Eg microvilli

Question 15

Are intermediate filaments more or less dynamic that microfilaments

Answer 15

Less

Question 16

What is the role of intermediate filaments in the cell (2)

Answer 16

Stabilise organelle position

Support cell structure

Question 17

What are intermediate filaments made from

Answer 17

Fibres: protein subunits vary

Question 18

What are the protein subunits of intermediate filaments found in epithelial cells

Answer 18

Keratin

Question 19

What are the protein subunits of intermediate filaments found in fibroblasts

Answer 19

Vimentin

Question 20

Roles of microtubules (5)

Answer 20

Cell division

Intracellular organisation

Transport tracks for motor proteins to move cargo

Muscle contraction

Power flagella and cilia

Question 21

What are microtubules made form

Answer 21

Long hollow tubules made from Polymers of tubulin

Question 22

Microtubules - made from polymers of tubulin - polymers f tubulin made from ……..

Answer 22

Alpha and beta tubulin

Question 23

What is a protofilament

Answer 23

Row of 10-15 alpha and beta tubulin that make up microtubules

Question 24

Are microtubules directional

Answer 24

Yes

Question 25

Microtubules are directional what does this mean

Answer 25

They have a + and - end

Question 26

What is found at the negative end of a microtubule

Answer 26

Capping protein

Question 27

Which end is the capping protein found on | What type of filament is r found on

Answer 27

Negative end of microtubule

Question 28

How are microtubules organised

Answer 28

Via microtubule organising centres

Question 29

Which end of microtubule is anchored in the microtubule organising centre

Answer 29

Minus end

Question 30

What is the primary microtubule organising centre in a cell called

Answer 30

Centrosome

Question 31

Where is the primary microtubule organising centre in a cell found

Answer 31

Near the nucleus

Question 32

Examples of motor proteins (2)

Answer 32

Dynein | Kinesin

Question 33

What are motor proteins

Answer 33

Proteins whose structure allows them to step along microfilaments or microtubules

Question 34

What to motor proteins require to move

Answer 34

ATP

Question 35

What blocks myosin binding sites at rests

Answer 35

Topomysin

Question 36

What moves tropomysin during muscle contraction

Answer 36

Calcium ions

Question 37

What does ATP do to myosin head

Answer 37

Detaches myosin head from myosin binding site

Question 38

What does release of ADP and Pi do to myosin head

Answer 38

Attached it to binding site

Question 39

What are flagella and cilia

Answer 39

Microtubule based projections of plasma membrane

Question 40

What are flagella and cilia built up from

Answer 40

Microtubules and dynein

Question 41

Filament role in disease (3)

Answer 41

Neurodegenerative disease Cancer Blistering skin disease

Question 42

Filament role in neurodegenerative disease

Answer 42

Neurofibrillary tangles in Alzheimer's disease

Question 43

Filament role in cancer

Answer 43

Error in mitosis

Question 44

Filament role in blistering skin disease

Answer 44

Epidermolysis simplex due to mutations in keratin