Lecture 5 Flashcards

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1
Q

What is the function of the cytoskeleton?

A

It allows movement, organization, and gives shape to the cell and organelles

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2
Q

What are the three filament types in the cytoskeleton?

A

Microfilaments, intermediate filaments, and microtubules

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3
Q

What are some subcellular structures that microfilaments organize into?

A

Microvilli, cell cortex, adherens belts, stress fibres, and contractile rings

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4
Q

What are microfilaments made of?

A

Actin monomers

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5
Q

What are the two states of actin?

A

G-actin (globular) and F-actin (filaments)

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6
Q

What occurs at the (-) end and the (+) end of an actin filament?

A

Depolymerization occurs at the (-) end and polymerization occurs at the (+) end

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7
Q

What does ATP bound actin favor?

A

Polymerization

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8
Q

What is the rate limiting step of actin polymerization?

A

Nucleation

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9
Q

What is a steady state?

A

When polymerization = depolymerization due to the concentrations of G-actin and F-actin being at equilibrium

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10
Q

How does the treadmilling of microfilaments generate force in the cell?

A

Treadmilling means that the microfilament is not changing in length, but it is moving in one direction. This movement is what generates the force.

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11
Q

What are actin sequestering proteins?

A

Proteins that bind at actin to prevent spontaneous polymerization.

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12
Q

What is profilin?

A

It enhances the loss of ADP off G-actin to increase the concentration of ATP-G actin

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13
Q

What is cofilin?

A

It binds to ADP-F actin and increases destabilization

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14
Q

What are myosins?

A

Myosins are ATP dependant proteins that can bind actin, undergo a conformational change, and move against the rigid actin CSK

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15
Q

What do all myosins contain?

A

An actin binding head domain, a flexible neck, and a tail domain

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16
Q

What does a myosin head domain bind to?

A

Actin and ATP

17
Q

What does a myosin tail domain bind to?

A

Cargo

18
Q

Where are microtubules anchored?

A

MTOC (centriole)

19
Q

Which end of the microtubule anchors in the MTOC?

A

The negative end

20
Q

Where are the positive ends of microtubules found?

A

Near the edges of the cell

21
Q

What is Gamma-TURC?

A

It is the nucleation site for microtubules

22
Q

How do microtubules facilitate CSK-based movement?

A

By constantly assembling and dissassembling themselves to generate force in a particular direction

23
Q

Which has a greater role in cellular movement: microtubules or microfilaments?

A

The treadmilling of microtubules

24
Q

What does catastrophe refer to?

A

The rapid disassembly of microtubules when GTPase activity catches up with the polymerization

25
Q

What are the two motors that are associated with microtubules?

A

Kinesins and dyneins

26
Q

What is the major difference between kinesin and dynein?

A

Kinesin is a (+) end directed motor and dynein is a (-) end directed motor

27
Q

How do kinesins move?

A

Via hand-over-hand movement

28
Q

How do dyneins move?

A

A power stroke that involves the rotation around the head domain

29
Q

What is the function of intermediate filaments in the nuclear lamina?

A

It forms a meshwork on the inner surface of the nuclear envelope that provides structural support to the nucleus