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BIOL 112 > 7 - cytoskeleton > Flashcards

7 - cytoskeleton Flashcards

1
Q

Three main types of fiber

A
  1. Microfilaments: About 7 nm in diameter and are composed of two actin chains twisted around each other. They have a variety of structural and locomotor functions
  2. Intermediate filaments: 8-10nm in diameter and are made up of a diverse group of proteins. Tend to be permanent fixtures, and are important in maintaining the shape of the cell, as well as maintaining the position of certain organelles
  3. Microtubules: Straight hollow rods 25nm in diameter and up to 20 microns long, and are constructed from globular proteins called Tubulins
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2
Q

Microfilaments

A
  • known for their role in the contraction of muscle cells where they interact with myosin filaments.
  • In addition to cell movement they are important in the maintenance of cell shape.
  • Microfilaments perform some structural roles in non-muscle cells, such as the formation of microvilli.
  • Most animal cells have a network of actin filaments just below the cell surface termed the Cell Cortex; this cortex supports the plasma membrane and facilitates cell movement.
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3
Q

True or false: many drugs work by targeting the cytoskeleton and the cytoskeleton remains a prime target for the development of new drugs

A

TRUE

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4
Q

The main role of intermediate filaments is contraction of muscle cells where they interact with myosin filaments. True or false?

A

FALSE- Intermediate filaments are important in maintaining the shape of the cell and holding organelles in their correct position - it is MICROFILAMENTS that are involved in muscle contraction

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5
Q

T/F?: G actin is a globular protein

A

TRUE

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6
Q

Which of the following are true?

a) F actin forms when soluble actin monomers polymerise
b) F actin is a soluble filamentous protein
c) F actin is a double right-handed helical molecule
d) F actin has a diameter of 14nm

A

a and c are true.
b is false because F actin is insoluble.
d is false because F actin has a diameter of 7nm

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7
Q

What is the Cell Cortex?

A

A network of actin filaments (microfilaments) just below the cell surface which supports the plasma membrane and facilitates cell movement

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8
Q

T/F?: Actin-myosin interactions are responsible for cytokinesis

A

TRUE - cytokinesis is the separation of daughter cells during mitosis - actin-myosin interactions are responsible for this

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9
Q

T/F?: The acrosome reaction in echinoderm sperm is driven by actin polymerisation

A

TRUE

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10
Q

T/F?: The movement of myosin along actin filaments requires ATP

A

TRUE

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11
Q

What are the two type of microtubules?

A

Axonemal and cytoplasmic

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12
Q

Axonemal microtubules

A

highly organised and stable, found in cilia, flagella and basal bodies

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13
Q

Cytoplasmic microtubules

A

more dynamic and loosely organised, found in cytoplasm

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14
Q

T/F?: Microtubules are formed from the polymerisation of tubulin dimers

A

TRUE

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15
Q

What are the proteins kinesis and cytoplasmic dynein involved in?

A

The movement of vesicles and small particles along microtubules

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16
Q

In which direction does kinesin and dynein travel along the microtubule?

A

Kinesin moves from the negative -> positive end.

Cytoplasmic dynein moves from the positive -> negative end

17
Q

The drug taxol is a microtubule/tubulin binding drug - true or false?

A

True - the drug taxol is a cancer drug used to treat ovarian cancer, lung cancer and breast cancer.
Taxol binds to microtubules and prevents disassembly so prevents cell division.

18
Q

What type of transport is the movement of kinesins?

A

Kinesins move from the negative end of the microtubule to the positive end - this is known as anterograde transport

19
Q

What type of transport is the movement of cytoplasmic dynein proteins?

A

Retrograde transport - dyneins move from the positive end of the microtubule to the negative

20
Q

T/F?: Cilia and flagella have the same lengths but different structures

A

FALSE - they have different lengths (cilia are around 2-20 microns - shorter whilst flagella are around 10-200 microns long- longer) but they have the SAME structure

21
Q

Describe the structure of cilia and flagella

A

They consist of a core of axonemal microtubules ensheathed in an extension of the plasma membrane

22
Q

T/F?: Cilia and flagella have a 9+2 arrangement of microtubules

A

TRUE

23
Q

T/F?: Intermediate filaments are capable of dynamic movement

A

FALSE - THEY ARE NOT

24
Q

T/F?: Intermediate filaments are 8-10nm in length and are soluble

A

FALSE - correct length but they are insoluble

BIOL 112 (12 decks)

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