Brainscape's Knowledge GenomeTM

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


See full index

M2M Exam 3 wk 3 > cytoskeleton I > Flashcards

cytoskeleton I Flashcards

1
Q

The cytoskeleton is a

A

dynamic intracellular structure (or set of structures) that serves to establish order within the cell as well as to organize the cells in their environment.

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

The cytoskeleton provides:

A
  1. Cell shape
  2. Mechanical strength
  3. The structures needed for locomotion
  4. Support for the plasma membrane
  5. The scaffold for the spatial organization of organelles
  6. 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
3
Q

The cytoskeleton is formed by

A

three different families of proteins that assemble to form large filamentous or tubular, non-covalent polymers, each with distinct mechanical properties, dynamics and functions.

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

The three types of cytoskeletal element are:

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

Role of Nucleotide
GTP:
Microtibules:

A

favors microtublue growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Accessory Proteins
Microtubules



A

Motor proteins:

  1. dyenins assembly/disassembly
  2. kinases

Assembly and disassemby

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

Accessory proteins of intermediate filaments

A
  1. assembly/dissasemby
  2. corss linking
  3. membrane anchor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Microtubule function

A
  1. movement of flagella and cilia

2. scaffold for cell organization and movement of organelles (including chromosomes)

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

intermediate filament function

A

mechanical stability

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

microtubule predominant protein:

A

tubulin a, B, y

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

intermediate filament predominant filament:

A

carious: vimentin, keratin, neurofilament proteins, GFAP

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

structure of microtubules

A

tubular

25 nm diameter

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

structure of intermediate filament

A

complex rope

10 nm diameter

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

By way of their architecture, microtubules have

A

α tubulin on one end and β tubulin on the other end. This confers polarity on the microtubule:

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

β tubulin =

α tubulin =

A

plus end

minus end

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

The GTP-bearing β subunits favor _____. In contrast, the α tubulin minus end tends to be _____

A

polymerization – the plus end is the end that grows

disassembling or shrinking.

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

As GTP-containing dimers become incorporated more deeply in to the MT,_____

A

GTP is hydrolyzed to GDP.

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

GDP weakens the

A

tubulin interaction in the protofilament

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Treadmilling is

A

growth at the plus end, disassembly at the minus end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

In response to a particular cellular activity, the plus end may lose its______.
This causes _______.

A

GTP-rich cap

rapid shrinkage from the plus end until GTP-containing dimers are added back

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

“dynamic instability” of the microtubule.

A
  1. MT capping proteins that bind to the ends of MTs usually increase their stability o MT severing proteins expose GDP-rich regions and thus promote MT instability
  2. Examples of severing proteins include Spastin and Katanin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Inhibitors of polymerization:

A
  1. Colchicine
  2. Vinblastine
  3. Vincristine
  4. Prevents microtubule growth – bad for the cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Stabilizers of polymerization:

A
  1. Paclitaxel (Taxol)
  2. Causes tubule and tubulin aggregates
    – bad for the cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Molecular motors:

A

Proteins that can transform the energy of ATP hydrolysis into motion (or walking) along microtubules, using MTs as “tracks.”

25
Q

There are two classes of molecular motor proteins:

A
  1. Kinesins: move cargo toward the plus-end

2. Dyneins: move cargo toward the minus-end

26
Q

Kinesins:

A

move cargo toward the plus-end

27
Q

Dyneins:

A

move cargo toward the minus-end

28
Q

Molecular motors have two important domains:

A
  1. Cargo-binding domain

2. Motor domain (or “head region”) – hydrolyzes ATP and reversibly minds to microtubules

29
Q

Mechanochemical Cycle of Motor Proteins

–Coordinated with ATP hydrolysis:

A
  1. MT binding
  2. Conformational change
  3. MT release
  4. Conformational relaxation o MT re-binding

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

30
Q

The mitotic spindle is constructed from :

A

MTs and associated proteins and serves to segregate the replicated chromosomes during mitosis.

31
Q

Three types of MTs can be distinguished:

A
  1. Astral MTs:
  2. Kinetochore MTs:
  3. Overlap MTs:
32
Q

Astral MTs:

A

radiate out from the centrosomes

33
Q

Kinetochore MTs:

A

attached to the kinetochore formed at the centromere of each duplicated
chromosome

34
Q

Overlap MTs:

A

interdigitate at the equator of the spindle

35
Q

In all cases, microtubule plus-ends point

A

away from the centrosomes (or spindle poles).

36
Q

Multimeric plus-end-directed, kinesin-like motor proteins bind to ____
and cause _____
This is enhanced by:

A

overlap MTs from opposite poles.

the spindle to grow and the centrosomes to become more distant.
pulling forces transmitted by astral MTs.

37
Q

cilia compared to flagella:

A

Cilia are shorter than flagella and are found in large numbers on the apical surface of epithelial cells (for example, those of the respiratory tract).

38
Q

The axoneme has a special structure called

A

a 9 + 2 array:

39
Q

The axoneme is responsible for

A

ciliary beating and can bend because of the highly coordinated action action of dynein activity.

40
Q

cilia function:

A

Beating with a whip-like motion in a staggered pattern, Cilia move fluids over the surfaces of cells

41
Q

Non-motile primary cilia serve special sensory functions:

A
  1. Photoreceptors (outer segment)
  2. Chemosensors (for example: olfactory neurons)
  3. Mechanosensors
42
Q

cilia in respiratory tract

A

In the respiratory tract, this action moves dust particles, bacteria, and mucus toward the mouth for elimination.

43
Q

Primary cilia or monocilia

A

occur singly in a great variety of cells and may or may not be motile.

44
Q

a 9 + 2 array:

A
  1. MTs and their associated proteins are arranged as a ring of 9 special doublets surrounding a pair of single microtubules
  2. Accessory proteins hold this array together o The axoneme is anchored in basal bodies
45
Q

The motor action of dynein heads causes microtubules to

A

slide against one another. When this sliding is prevented by microtubule anchoring, as in the axoneme, bending results.

46
Q

diseases of intermediate filaments:

A
  1. epidermolysis bullosa simplex (keratin)
  2. charcot marie tooth (neurofilament)
  3. ALS (neurofilaments)
  4. progeria (lamins)
47
Q

epidermolysis bullosa simplex

A
  1. Keratin mutations may interfere with filament assembly.

2. The resulting epidermis is highly sensitive to mechanical stress and blisters easily

48
Q

Charcot-Marie-Tooth Syndrome

A

Mutations in the light chain may interfere with axonal transport of neurofilament subunits and

peripheral neuropathy

49
Q

Amyotrophic Lateral Sclerosis (ALS)

A

Abnormal neurofilament assembly seems to be involved in the neurodegenerative
disease

50
Q

Progeria Syndroms

A

Mutations in lamins can result in nuclear instability

51
Q

microtubule diseases

A
  1. primary ciliary dyskinesia syndrome (dynein)

2. peripheral neuropathy

52
Q

peripheral neuropathy

A
  1. Mitosis serves as a major drug target.
  2. MT toxins block mitosis and, thus, are important therapeutic tools for cancer treatment.
  3. They may adversely affect other MT functions, such as
  4. axoplasmic transport
53
Q

primary ciliary dyskinesia syndromes

A
  1. mutation in dynein motor
  2. Photoreceptor outer segments are modified monocilia
  3. That such cilia may operate as chemosensors
    - -Anosmia
  4. That establishment of left/right identity requires normal function of monocilia on nodal cells during gastrulation
54
Q

Anosmia

A

probable explanation for cyst formation in developing kidney

55
Q

Examples of cytoplasmic IFs:

A

1) Vimentins
2) Keratins,
3) Neurofilament proteins
4) Glial fibrillary acidic protein (GFAP)

56
Q

Vimentins are present

A

in a majority of cell types.

57
Q

Keratins:

A

a family of about 50 proteins, are dominant components of the epidermis and its appendages, providing mechanical strength.

58
Q

Neurofilament proteins

A

co-assemble to form neurofilaments, which are found in high concentration in vertebrate axons. Neurofilament abundance appears to control axonal diameter.

59
Q

Glial fibrillary acidic protein (GFAP) is the

A

IF protein characteristic of astrocytes in the CNS. Therefore, GFAP IFs are abundant in connection with inflammatory and/or degenerative processes in the brain. For example, Alzheimer plaques are surrounded by GFAP-rich reactive astrocytes.

M2M Exam 3 wk 3 (11 decks)

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