Cytoskeleton Flashcards

1
Q

What is the cytoskeleton?

A

Cytoskeleton—>network of fibres that extends throughout the cytoplasm
o Involved in maintaining and organizing structure of cell

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2
Q

What is cytosol?

A

> Cytosol: The semi-fluid portion of the cytoplasm

Cytosol—> h2O and dissolved ions, proteins, carbohydrates, nucleic acids

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3
Q

What are the roles of the cytoskeleton? (4)

A

• Mechanical support—> maintains shape
o Important in animal cells due to the lack of cell wall
• Provides anchorage for cell organelles
• Dynamic structure
o Can be disassembled, or de-polymerized, in one part of the cell and then reassembled in another part—> Changes the shape of the cell
• Involved in cell motility—> changes to cell location and movement of cell parts
o Requires interaction between cytoskeleton elements and motor proteins
o Above two work with the plasma membrane and cause cells to move along fibre networks outside of a cell
o Inside cells organelles and vesicles often use motor proteins to walk along tracks provided by the cytoskeleton to their destinations

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4
Q

What are the three components of the cytoskeleton?

A

• Cytoskeleton consists of three components:

  1. Microtubules—> the thickest of the three
  2. Microfilaments—> the thinnest of the three
  3. Intermediate filaments—> fall intermediate to the thickness of microtubules and microfilaments
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5
Q

What is the cytoplasm?

A

Cytoplasm:

> made from cytosol and cell organelles embedded within the cell cytoplasm

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6
Q

How is the cytosol separated?

A

> Cytosol is fundamentally separated from the organelles and their inner components as they are membrane-bound

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7
Q

The contents of the cell are bounded by the ____ membrane.

A

plasma

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8
Q

How does the cytoskeleton manipulate the cell membrane?

A

The cytoskeleton can also manipulate the cell membrane to form phagocytosis and hence form vacuoles from the invagination in the cell membrane engulfing a food particle or other.

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9
Q

Define what the cytoskeleton is?

A

Cytoskeleton: a network of microtubules, microfilaments and intermediate filaments that extend throughout the cytoplasm and serve a variety of mechanical, transport, dynamic and signal functions.

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10
Q

How are the cilia and flagella formed?

A

Cilia and flagella are formed fundamentally by sub-units made from the cytoplasm.

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11
Q

What is the nuclear lamina (lines the inner surface of the nuclear membrane)? (2)

A

> a dense fibrillar network inside the nucleus of most cell nuclei.
made up of many intermediate filaments and membrane-associated proteins that all work collectively to provide nucleus structures and anchorage (General mechanical support)

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12
Q

Microtubules
• Straight ____ rods
• 25nm in diameter and 200nm to 25um in length
• Are able to ______ move and reassemble

A

hollow

disassemble

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13
Q

What is the composition of microtubules?

A

Globular proteins: alpha-tubulin and beta-tubulin

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14
Q

What is the function of the microtubules? (3)

A
  • Shape and support the cell
  • Provide tracks along which organelles can move
  • Cell motility
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15
Q

Where do microtubules grow out from?

A

Microtubules grow out from the centrosome

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16
Q

What are centrioles?

A

In the centrosome of the animal cells, there are a pair of centrioles
• Centriole is composed of 9 sets of triplet microtubules arranged in a ring

17
Q

What do centrioles do?

A

Centrioles help organize microtubule assembly

18
Q

What is the centrosome? (3)

A
  • an organelle near the nucleus of a cell that contains the centrioles (in animal cells) and from which the spindle fibres develop in cell division.
  • centrioles are found at right angles to each other; the centrosome is the microtubule origin site
  • a set of microtubules triplets surround the inner cavity
19
Q

What are the functions of the cilia and flagella?

A

motility of cells

20
Q

Flagella are ____ structures and few in number, while cilia are ____ and numerous.

A

long

short

21
Q

What is the structure of cilia and flagella? (2)

A

• Structure—> central core of two microtubules is surrounded by 9 doublets of microtubules
(9+2 pattern)
• Doublets have attached motor proteins, the dynein arms, that help bend the flagella

22
Q

Size of microfilaments: solid rods approximately ___ in diameter.

23
Q

What is the composition of microfilaments?

A

Composition—>built from two intertwined strands of actin, a globular protein

24
Q

What is the function of microfilaments? (3)

A
  • Aid in the contraction of muscles
  • Microfilaments are attached to myosin
  • Contraction of the cell results in actin and myosin microfilaments sliding past one another, this shortens the cell—>see muscle contraction (m line, z line, ADP, ATP, myosin, actin, myosin head)
25
How does muscle contraction work? (4)
> actin filaments (microfilaments) are connected to myosin filaments containing myosin heads > The myosin heads/ projections walk and causes the contraction of actin filaments parallel to the myosin movement > This causes muscle cell contractions > Muscle contraction involves many muscle cell contractions simultaneously and in sync
26
What is the size of intermediate filaments?
8-12nm in diameter
27
True or false | Intermediate filaments are more permanent structures than microtubules and microfilaments
True
28
What is the composition of intermediate filaments? (2)
* Several proteins like keratins | * Fibrous proteins coiled
29
What is the function of intermediate filaments?
• Providing structure to the cell, and anchoring of organelles within the cell