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Cell Bio > Chapter 9: The cytoskeleton and cell motility > Flashcards

Chapter 9: The cytoskeleton and cell motility Flashcards

1
Q

3 elements of the cytoskeleton:

A
  • microtubules
  • microfilaments
  • intermediate filaments
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2
Q

Roles of the cytoskeleton

A
  • structural support/maintaining cell shape
  • internal framework organizing organelles within the cell
  • directs cellular locomotion and movement of materials within the cell
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3
Q

T/F: Microtubules are highly branched

A

FALSE. Microtubules are long, hollow, UNBRANCHED tubes

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4
Q

microtubues are composed of subunits of the protein ____

A

tubulin

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5
Q

Microfilaments are ccomposed of the protein ____

A

actin

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6
Q

a MICROTUBULE is a set of GLOBULAR proteins arranged in longitudinal rows called _________

A

PROTOFILAMENTS

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7
Q

How many protofilaments does a microtubule contain?

A

13

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8
Q

each PROTOFILAMENT is assembled from dimers of ___ and ____ subunits assembled into tubules with plus and minus ends.

A

dimers of ALPHA and BETA tubulin subunits

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9
Q

is the core of cilia and flagella is composed of microtubules or microfilaments?

A

MICROTUBULES

…ya ninny

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10
Q

what does MAPs stand for?

A

Microtubule-associated proteins

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11
Q

How is the microtubule-binding activity of MAPs controlled?

A

primarily by the addition and removal of PHOSPHATE GROUPS from particular AMINO ACIDS

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12
Q

T/F: MAPs attach to the surface of microtubules to increase their STABILITY and promote their ASSEMBLY

A

True.

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13
Q

What is one cause of Alzheimer’s disease related to MAPs?

A

an abnormally high level of phosphorylation of a certain MAP called “tau.”
The brain cells of people with this disease contain tangled filaments called NEUROFIBRILLARY TANGLES containing excessively phosphorylated tau molecules that are UNABLE TO BIND to MICROTUBULES, contributing to death of nerve cells.

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14
Q

the movement of vesicles and material in the axon is mediated by _________

A

microtubules

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15
Q

What generate the forces required to move objects within a cell?

A

motor proteins

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16
Q

T/F: Microtubules have no role in embryogenesis.

A

False. Microtubules play a role in AXONAL GROWTH during embryogenesis

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17
Q
  1. movement of material AWAY from the cell body

2. movement of material TOWARDS the cell body

A
  1. anterograde

2. retrograde

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18
Q

T/F: molecular motors can move in any direction.

A

False. Molecular motors move UNIDIRECTIONALLY along the cytoskeletal track in a stepwise manner.

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19
Q

3 classes of molecular motors:

A
  1. kinesin
  2. dynein
  3. myosin
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20
Q

Along what tracks do kinesin, dynein, and myosin move?

A

Kinesin and dynein move along MICROTUBULE TRACKS.

Myosin moves along MICROFILAMENT TRACKS.

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21
Q

Motor proteins convert ____ energy into ____energy.

A

chemical energy (ATP) into mechanical energy.

22
Q

Which motor protein family moves in an anterograde manner along the microtubule track and which moves in a retrograde manner?

A 
kinesin = anterograde
dynein = retrograde
23
Q

What drives the stepwise movement of motor proteins?

A

binding and hydrolysis of ATP

24
Q

What does “KLPs” stand for?

A

kinesin-like proteins

25
Q

composition of kinesins

A
  • 2 identical heavy chains
  • 2 identical light chains
  • each kinesin includes a PAIR OF GLOBULAR HEADS connected to a ROD-LIKE STALK.
26
Q

T/F: kinesin is a PLUS end-directed microtubular motor based on its movement

A

true

27
Q

What is the velocity of the movement of kinesin on a single protofilament of a microtubule proportional to?

A

ATP concentration

28
Q

Explain “processive movement”

A

movement of KINESIN is PROCESSIVE, meaning it moves along an individual microtubule for a long distance without falling off.

29
Q

KLPs move cargo towards the __________

A

cell’s PLASMA MEMBRANE

30
Q

What movement is dynein responsible for?

A

the movement of CILIA and FLAGELLA

31
Q

Cytoplasmic dynein is a _____ end directed microtubular motor

A

minus

32
Q

Name of adaptor required by cytoplasmic dynein to interact with membrane-bounded cargo:

A

dynactin

33
Q

Kinesins move cargo in one direction, towards the ___ end, and the dyneins move it in the opposite direction, towards the ____ end.

A

Kinesins move cargo in one direction, towards the PLUS end, and the dyneins move it in the opposite direction, towards the NEGATIVE end.

34
Q

T/F: kinesins and dyneins are ATPases

A

true

35
Q

What are MTOCs?

A

“microtubule-organizing centres”
Specialized structures for the NUCLEATION of MICROTUBULES.
ex. centrosome

36
Q

What is the centrosome responsible for?

A

-initiation and organization of the microtubular cytoskeleton

37
Q

T/F: centrioles are usually found in groups of 4

A

false. Centrioles are usually found in pairs

38
Q

Centrosomes contain 2 barrel-shaped _______ surrounded by ________

A

Centrosomes contain 2barrel-shaped CENTRIOLES surrounded by PERICENTRIOLAR MATERIAL (PCM)

39
Q

Basal Body

A
  • MTOC

- structure where outer microtubules in a cilia and flagella are generated

40
Q

Do plants conatin MTOCs? Where are their microtubules organized?

A

Plants DO NOT contain MTOCs. THeir microtubules are organized around the surface of the nucleus.

41
Q

What is the name of the protein which is found in MTOCs and is critical for microtubule nucleation?

A

γ-tubulin

42
Q

What does γ-TURC stand for?

A

γ-TUbulin Ring Complex

43
Q

γ-TURC complex forms a polypeptide scaffold on which ____γ-tubulin molecules are arranged

A

13

44
Q

Hydrolysis of what molecule is needed for microtubule assembly?

A

GTP

45
Q

Proteins called ____ regulate the rate of growth and shrinkage of microtubules

A

+TIPS

46
Q

Axoneme

A
  • central core of cilia and flagella.

- consists of microtubules in a 9 + 2 arrangement

47
Q

the CENTRAL SHEATH of the axoneme is connected to the a-tubules of peripheral doublets by ____

A

radial spokes

48
Q

By what are doublets in an axoneme connected to one another?

A

by an INTERDOUBLET BRIDGE

49
Q

What is IFT?

A
  • “intraflagellar transport”

- process responsible for assembling and maintaining flagella

50
Q

T/F: basal bodies are identical in structure to centrioles

A

true. basal bodies can turn into centrioles and vise versa

Cell Bio (4 decks)

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