Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Thanh Cell Physiology Unit III > Cytoskeleton I &II > Flashcards

Cytoskeleton I &II Flashcards

1
Q

cytoskeleton

A

Dynamic intracellular structure - does lots of things for cell

provides:
o Cell shape
o Mechanical strength
o Structures needed for locomotion
o Support for the plasma membrane
o The scaffold for the spatial organization of organelles
o The means for intracellular transport of organelles and other cargo.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The three types of cytoskeletal element

A
  1. microfilaments
  2. microtubules
  3. intermediate filaments
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

microtubule structure/properties

A

tubular structures, one end attached to centrosome

GTP favors microtubule growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

microtubule predominant proteins

A

tubulin: alpha, beta, gamma

typically building blocks of heterodimers of tubulin protein (alpha and beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

microtubule function

A
  1. Movement of flagella and cilia
  2. cellular cytoskeleton (scaffold)
  3. intracellular transport
  4. cell division
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Intermediate filament structure/properties

A

complex ropelike filament made from 8 tetramers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Intermediate filament predominant proteins

A

vimentin
keratin
neurofilaments
GFAP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Intermediate filament function

A

mechanical stability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does GTP affect microtubule growth?

A

GTP favors microtubule growth of the plus end (beta subunit)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How do microtubules confer polarity?

A

they have an alpha tubulin on one end (minus), and a beta tubulin (plus) on the other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe treadmilling

A

growth at plus end, disassembly at minus end due to GTP hydrolyzing to GDP,

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

describe dynamic instability of microtubules

A

MT capping proteins can bind to ends to increase stability

MT severing proteins can expose GDP rich regions and increase instability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

2 examples of severing proteins

A

Spastin and Katanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

plant Drugs that inhibit MT polymerization

A

the “ines”
cholchicine
vinblastine
vincristine

  • prevents MT growth = bad for cell
  • blocks mitosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Drug that stabilize polymerization

A

paclitaxel (taxol)

causes tubulin aggregates = bad for cell
-blocks mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

kinesins
dynesins

which direction is cargo being moved?

A

molecular motors - prime sites of regulation

kinesins: move cargo towards plus end
- (need adaptors since they do not directly bind to cargo)

dynesins: move cargo towards minus-end
- only GDP bound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Mechanism of tubilin based movement and intracellular transport

A

Coordinated with ATP hydrolysis - when either head is bound to ATP it binds to MT.

o MT binding 
o Conformational change
o MT release
o Conformational relaxation
o MT re-binding

This process moves the motor protein and the cargo along the microtubule in a stepwise fashion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Different types of microtubules (MT) associated with mitosis

A
  1. astral MT
  2. Kinetochore MT
  3. Overlap MT
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the mitotic spindle made of?

A

MTs and associated proteins

20
Q

What is the only case where 2 centrosomes can be seen?

A

A cell about to undergo mitosis

before cytokinesis

21
Q

Role of microtubule (MT) in mitosis (cell division)

A
  1. microtubule plus ends point away from the centrosome (mitotic spindles)
  2. The motors, astral MT, (and other proteins) cause spindle to grow and centrosomes to become more distant.
  3. minus end directed motors separate daughter chromosomes and move them along MT to centrosome
22
Q

Of the 3 types of cytoskeletal elements, which ones are polarized and which one is not?

A

polarized: MT, MF

Nonpolar: NF
-no plus or minus end

23
Q

axoneme

  • what is it?
  • what allows it to bend?
A

microtubule core of cilia and flagella

  • the highly coordinated action of dynein activity
24
Q

Intermediate filament disease associated with Keratins

A

interferes with filament assembly
- epidermis highly sensitive to mechanical stress/blisters

= Epidermolysis bullosa simplex

25
Q

Intermediate filament disease associated with Neurofilaments

A

interferes with axonal transport of neurofilaments

=charcot marie tooth
=Amyotrophic lateral sclerosis (ALS)

26
Q

Intermediate filament disease associated with Lamins

A

results in nuclear instability

=progeria syndromes (weird alien head)

27
Q

Disease associated with mutation in dynein motor

A

outer cilia/flagella are missing

=primary ciliary dyskinesia syndrome

28
Q

What is another name for centrosome? Where is it located?

A

perinuclear microtubule organizing center (MTOC)

located near the nucleus

29
Q

What is another name for microfilaments?

A

actin cytoskeleton

30
Q

microfilament structure/properties

A

helical filaments

ATP promotes actin polymerization

(remember tubulins bind GTP)

31
Q

microfilament predominant protein

A

G-actin monomers

32
Q

microfilament function

A

cell shape
movement
polarity
cell division

33
Q

2 steps in microfilament formation

A
  1. nucleation

2. extention/retraction of actin filament

34
Q

describe role of proteins in actin filament nucleation

A

actin nucleation (new actin production) involves:

  1. Actin related proteins (ARP2/3) which leads to branched filaments.
    or
  2. FH2 which leads to parallel filaments
35
Q

describe role of proteins in actin extention/retraction

polymerization/depolymerization

A

Preventing polymerization:

  1. profillin binds to actin
  2. capping proteins cap the plus/minus end

Induce depolymerization
1. cofilin severs actin filaments and induces depolymerization

36
Q

actin cytoskeleton role in epithelial cell polarity

name what disease is associated with loss in function

A

actin anchors PROTEINS involved in tight junctions and adherens junctions that hold epithelial cells together

loss of cell adhesion = increase in cell motility = epithelial to mesenchymal transition = cancer

37
Q

what are molecular motors? example?

A

proteins that can transform energy from ATP hydrolysis into motion.

myosin: actin associated moter proteins

38
Q

Myosin structure

A 
2 heads
  - 1 binds actin
  - 1 binds ATP
1 Tail
  - binds cargo
39
Q

Myosin 3 main classes and function

A

Myosin II
- muscle contraction: myosin filaments walk along actin thin filaments towards plus end during muscle contraction

Myosin I + V:
- unconventional myosin and binds to organelles/vesicles thru tails and moves them along actin filaments

40
Q

Concept of cell movement (motility)

A

cells commonly translocate by amoeboid movement. Amoeboid movement is governed largely by changes in actin cytoskeleton, induced by extracellular signals.

41
Q

Key steps of cell movement (motility/amoeboid locomotion)

think of picture

A
  1. protrusion: signal from Rac and WASp causes actin to polymerize (catalyzed by Arp 2/3) and form projection called lamellipodia and Filopodia
  2. attachment: lamellipodia protrusions attach with substratum ahead
  3. traction: cell is pulled forward by tension created by anchored actin protrusions and myosin molecular motors
  4. detachment: adhesions behind new sites of anchorage are released to allow for translocation
42
Q

Filopodia

A

result from polymerization catalyzed by formins

have attached receptors for ‘sampling’ the environment in front of the cell during movement

43
Q

role of actomyosin ring in cell division

A

actomyosin ring: ring structure with associated myosins that form around a dividing cell

it contracts through action of myosin heads and ATP hydrolysis during cytokinesis to separate daughter cells.

44
Q

mechanism regulating the establishment and activation of actomyosin ring

A

the site and timing of contraction of the actomyosin ring regulates the symmetry of cell division
(could result in assymetric cell division)

Rho-GTP activates 1 of 2 pathways for contraction of ring

  1. activates formin
  2. activates Rock kinase
45
Q

examples of asymmetric cell division

A
  1. red blood cells: nucleus is separated from remainder of cell in cytokinesis
  2. platelet formation: cell duplicates its genetic material before dividing, and later divides assymetrically many times to give rise to many cell fragment (megakaryotypes)
  3. sperm development: cells can be left connected by canals by persistence of actomyosin ring following division until ready to be released and cleavage occurs
  4. division of epithelial cells ensures cells maintain a monolayer distribution (not stacked)

Thanh Cell Physiology Unit III (26 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions