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Cell Biology > Cytoskeleton > Flashcards

Cytoskeleton Flashcards

1
Q

What is the cytoskeleton?

A

A filamentous structure found throughout the cytoplasm

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2
Q

What is the cytoskeleton formed of?

A

Protein monomers which assemble into repeat structures

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3
Q

What 3 types of filaments are found in the cytoskeleton?

A

Actin
Microtubules
Intermediate filaments

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4
Q

What is the main property of the cytoskeleton?

A

It is dynamic - can assemble and disassemble rapidly to suit the cells needs

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5
Q

What is the function of the cytoskeleton?

A

To provide stability and support to the cell

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6
Q

What can link to the cytoskeleton?

A

Other cellular components

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7
Q

What are motor proteins?

A

Proteins that move organelles along filaments and filaments against each other

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8
Q

What is the diameter of an actin filament?

A

5-9nm

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9
Q

What are actin filaments made of?

A

Actin = globular protein

- Actin assembles into two stranded helical polymers

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10
Q

What can actin helical polymers form?

A

3D gels
2D networks
Bundles - by lining up

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11
Q

What are the functions of actin filaments?

A

Shape

Motility

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12
Q

Where are actin filaments found?

A

Throughout the body but mainly concentrated beneath the cortex

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13
Q

What is the diameter of a microtubule?

A

25nm

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14
Q

What are microtubules made of?

A

Tubulin = globular protein containing alpha and beta subunits
- Long and straight

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15
Q

What structure does tubulin form in microtubules?

A

Hollow tubes

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16
Q

How do microtubules compare to actin filaments in terms of rigidity?

A

More rigid

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17
Q

What are microtubules typically attached to?

A

Centrosomes at one end

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18
Q

What is a centrosome?

A

A microtubule organising centre

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19
Q

What does the end of the microtubule not attached to the centrosome do?

A

Grow and shrink

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20
Q

What are the functions of microtubules?

A

Positioning of organelles
Mitosis
Intracellular transport

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21
Q

What is the diameter of an intermediate filament?

A

10nm

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22
Q

What is the function of intermediate filaments?

A

Mechanical support

23
Q

What are intermediate filaments made of?

A

Various intermediate filament proteins which are individually filamentous

24
Q

What are dimers within intermediate filaments?

A

Extended alpha helical regions which are wound together

25
Q

What are tetramers and how are they formed?

A

Soluble subunits formed by the association of dimers

26
Q

What to tetramers wind to form?

A

Rope-like fibres

27
Q

How is the cytoskeleton formed?

A

Monomers form end-to-end and side-to-side interactions that are non-covalent and therefore can be broken and formed easily for rapid assembly and disassembly

28
Q

What does the relative strength of end-to-end and side-to-side interactions formed between monomers determine?

A

Mechanical strength

29
Q

What is the rate of monomer addition relative to?

A

Monomer concentration

30
Q

What happens when there is a critical concentration of monomers?

A

There is no net growth

31
Q

What type of ends do actin filaments and microtubules have?

A

Fast and slow growing = + and -

32
Q

What additional proteins may be associated with nucleation?

A

Auxiliary proteins which may act as an initiator for a new filament

33
Q

What additional proteins may be associated with assembly?

A

Proteins which bind monomers depending on their relative concentration

34
Q

What additional proteins may be associated with disassembly?

A

Proteins which can bind and either stabilise or destabilise filaments

35
Q

What property of the cytoskeleton might toxins affect? Give two examples

A

Their ability to disassemble or control of actin filaments

  • taxol = stabilises microtubules
  • colchicine = binds free tubulin
36
Q

What is myosin?

A

An actin based motor protein

37
Q

How many myosin genes are there in a human?

38
Q

What type of myosin makes muscles contract?

39
Q

How are myosin long domains formed?

A

By the coiling of two mysoin II heavy chains

40
Q

What do tail domains interact with?

A

Other myosin parts forming large bipolar ‘thick myosin’

41
Q

What do globular myosin heads contain?

A

Force generating machinery

42
Q

What are kinesin and dynein?

A

Microtubular motor proteins

43
Q

Which part of kinesin and dynein interacts with the cytoskeleton?

A

Myosin heads

44
Q

What way does kinesin move organelles?

A

From the - to the + end of the microtubule

45
Q

What way does dynein move organelles?

A

From the + to the - end of the microtubule

46
Q

Where in the cell is the golgi retained and what molecule is retained by?

A

Close to centrosomes by dynein

47
Q

Where in the cell is the ER dispersed and by what molecule?

A

To the cell periphary by kinesin

48
Q

How are vesicles moved within a cell?

A

Along microtubules

- From the golgi to ER by dynein

49
Q

What is cell crawling and what types of cells does it occur in?

A

The rearrangement of actin in the cytoskeleton

  • Macrophages
  • Neutrophils
50
Q

What are flagella and cilia and what are they composed of?

A

Tubular structures composed microtubules

51
Q

How do flagella and cilia move?

A

Ciliary dynein causes microtubules to slide across one another allowing the flagella/cilia to propel the cell forward

52
Q

What is found at the tip of microvilli?

A

Bundles of actin filaments

53
Q

How do microvili move?

A

Myosin attached to the cell membrane moves the actin filaments causing the microvili to ‘wave’

Cell Biology (11 decks)

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