Muscle 1

Question 1

What does the cytoskeleton consist of

Answer 1

1. Microtubules
2. Microfilaments
3. Intermediate filaments

Question 2

What components of the cytoskeleton have roles in cellular shape & cell movement

Answer 2

Microtubules & microfilaments

Question 3

What are microtubules made of

Answer 3

Polymers of alpha and beta tubulin

Question 4

How are polymers of alpha an beta tubulin made

Answer 4

Spontaneously within the cell

Question 5

How are alpha and beta tubulins assembled

Answer 5

Intro repeated dimeric unites to create microtubules

Question 6

Stages of microtubule formation

Answer 6

1. Alpha-tubulin & beta-tubulin combine to form a dimer, tubulin
2. Multiple dimers assemble end-to-end to from a protofilament
3. Protofilaments line up to form a sheet
4. Sheet of protofilaments roll up to form a tube
5. Microtubule grows by monomer addition to + end and shrinks by monomer removal from - end

Question 7

How can microtubules be stabilized to from a polarized cellular network

Answer 7

Microtubule associated proteins (MAP) & Microtubule organizing centers (MTOC)

Question 8

How are vesicles transported in the axon

Answer 8

Microtubules in conjunction with either Kinesin & Dynein

Question 9

What direction of transport is Kinesin responsible for

Answer 9

Away from cell body

Question 10

What direction of transport is Dynein responsible for

Answer 10

Towards the cell body

Question 11

What are microfilaments

Answer 11

Polymers of actin

Question 12

How can the cell move when considering microfilaments

Answer 12

The controlled polymerization of actin

Question 13

What is myosin

Answer 13

Actin-binding motor protein

Question 14

How many classes of myosin are eukaryotes

Answer 14

17

Question 15

What is Myosin II

Answer 15

Muscle myosin

Question 16

What are Myosins I and V

Answer 16

Myosin in intracellular trafficking

Question 17

Which myosins work as dimers

Answer 17

Myosin II and V

Question 18

Which myosins have ATPase activity

Answer 18

All of them

Question 19

Where is the ATPase activity in myosin

Answer 19

The head

Question 20

How are light chains regulated

Answer 20

Phosphorylation

Question 21

What is a consequence of phosphorylation of light chains

Answer 21

They influence the catalytic activity of the ATPase of the myosin heavy chain head

Question 22

What are the components of myosin

Answer 22

1. Head
2. Neck
3. Tail

Question 23

What are the components of the neck in myosin

Answer 23

Myosin I and V: Calmodulin light chains

Myosin II: Essential light chain & Regulatory light chain

Question 24

How long are myosin (on average)

Answer 24

130 mm

Question 25

What are allosteric "walking proteins"

Answer 25

Myosin

Question 26

How are myosin "walking proteins"

Answer 26

By walking along actin filaments

Question 27

What is unitary displacement when talking about myosin

Answer 27

Myosin movement that proceeds in steps

Question 28

What is myosin step length dependent on

Answer 28

Length of the myosin's neck

Question 29

What model is used for muscle contraction

Answer 29

Myosin, actin, and the sliding filament model

Question 30

Cross-bridge cycle steps

Answer 30

1. Myosin un-cocked and unbound (after ATP-bound) 2. Myosin cocked and unbound (after ATP hydrolysis) 3. Myosin cocked and bound 4. Power stroke (after Phosphate leaves) 5. Myosin uncocked and bound (after ADP release)

Question 31

What is the Duty Cycle

Answer 31

Steps 3-5 of the Cross-bridge cycle 3. Myosin cocked and bound 4. Power stroke (after Phosphate leaves) 5. Myosin uncocked and bound (after ADP release)

Question 32

What does myosin bind to

Answer 32

Actin

Question 33

How is myosin binding to actin regulated

Answer 33

Ca 2+, troponin, and tropomyosin

Question 34

What are the thin filament proteins implemented in muscle contraction

Answer 34

Troponin and tropomyosin

Question 35

What causes contraction of the myofibril/cardiomyocyte

Answer 35

Increase in intracellular Ca 2+