Brainscape's Knowledge GenomeTM

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


See full index

Cell Biology (BY1CB1) > Week 9 (cytoskeleton) > Flashcards

Week 9 (cytoskeleton) Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is the cytoskeleton?

A

an intricate network of protein filaments that extends throughout the cell

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

What are the Functions of the cytoskeleton?

A

-Controlling the location of the organelles
•Providing machinery for transport between organelles
•Segregating chromosomes into two daughter cells at cell division and pinching apart those two new cells

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

Cytoskeleton proteins- What are actin filaments?

A
  • The thinnest filaments of the cytoskeleton, a structure found in the cytoplasm of cells. These linear polymers of actin subunits are flexible and relatively strong, resisting buckling due to compressive forces and filament fracture by tensile forces on the cells.
  • Each actin molecule has binding sites for Mg2+ ion with either ATP or ADP bound.
  • Actin exists in two principal forms, i.e. globular monomeric form (G) and filamentous polymeric form (F).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the regulation of Actin- Actin Binding Proteins:
Motor proteins
e.g. Myosin

A

Move along actin filaments carrying a cargo

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

Regulation of Actin- Actin Binding Proteins: Crosslinking proteins
e.g. α actinin

A

Crosslink actin into higher-order assemblies or to other structures, such as plasma membrane

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

Regulation of Actin- Actin Binding Proteins: Nucleating

e.g. Formin

A

Initiating the formation of new filaments as branched networks

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

Regulation of Actin- Actin Binding Proteins: capping

A

Caps filament ends to prevent polymerization

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

Regulation of Actin- Actin Binding Proteins: monomer binding

A

Profilin: binds to actin monomer and accelerates elongation
Thymosin: binds and locks actin monomer
Cofilin: binds and destabilizes ADP-actin filaments (depolymerization)

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

Regulation of Actin- Actin Binding Proteins: Filament binding
e.g. Tropomyosin

A

Stabilizing filament

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

Regulation of Actin- Actin Binding Proteins: severing e.g thymosin

A

Depolymerizing actin filament

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

Cytoskeleton proteins- Actin Filaments: cellular functions

A

Determines the shape of the cell’s surface
•Whole-cell locomotion
•Cell division

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

Cytoskeleton proteins- Actin Filaments: Physiological functions (in association with Actin Binding proteins)

A

Body muscle contraction

•Heart function

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

Cytoskeleton proteins- Actin Filaments: Dysfunctions

A

Congenital myopathies

•Actin-accumulation myopathy (severe muscle weakness (myopathy) and poor muscle tone (hypotonia) throughout the body)

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

Cytoskeleton proteins- Microtubules

Filaments

A

Filaments
•Microtubules
A component of the cytoskeleton, found throughout the cytoplasm. These tubular polymers of tubulin can grow as long as 50 micrometres and are highly dynamic. The outer diameter of a microtubule is about 24 nm while the inner diameter is about 12 nm.

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

Cytoskeleton proteins- Microtubules

Structure of microtubules

A

Structure of microtubules
•There are two types of tubulin molecules, α tubulin and β tubulin, which form a heterodimer.
•Both α monomer and β monomer can bind to GTP. GTP bound to the α-tubulin is trapped at the dimer interface and is never hydrolysed or exchanged, while the β-tubulin can bind to either GTP or GDP.

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

Stabilizing MAPs

A

MAP2: binds along the microtubule lattice and stabilizes microtubules
Tau: possesses a microtubule crosslinking domain
Plectin: links to intermediate filaments

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

What are MAPs?

A

Microtubule Associated proteins

18
Q

Destabilizing MAPs

A

E.g. Stathmin: binds tubulin dimers prevents assembly

Katanin: severs microtubules

19
Q

MAPs: Plus end track protein

A

XMAP215: stabilizes plus ends and accelerates assembly

Plus end tracking proteins (+TIPs): remain associated with growing plus ends and can link plus ends to other structures

20
Q

MAPs: Motor Proteins

A

E.g. Kinesins and Dyneins, transport cargo and perform a variety of other cellular functions.

21
Q

Which Specialized Organelles are associated with microtubules?

A

Cilia and centrioles

22
Q

Cytoskeleton proteins- Microtubules: cellular functions

A

Localizing and transporting organelles

•Cell division

23
Q

Cytoskeleton proteins- Microtubules: physiological functions

A

Neuron migration

•Motile cilia: clearing dirt, dust, micro-organisms and mucus, to prevent disease

24
Q

Cytoskeleton proteins- Microtubules: dysfunctions

A

Alzheimer’s disease (Hyperphosphorylation of Tau)

25
Q

Cytoskeleton proteins-Intermediate Filaments

Describe their properties compared to other filaments

A

-With an average diameter of 10 nanometers, which is between that of 7 nm actin (microfilaments), and that of 25 nm microtubules, and they were initially designated ‘intermediate’ because their average diameter is between those of narrower microfilaments (actin) and wider myosin filaments found in muscle cells.
-Their core structure is an α-helical coiled coil.
Intermediate filaments are prominent in cytoplasm of cells that are subject to mechanical stress.

26
Q

Cytoskeleton proteins-Intermediate Filaments

Describe their structure

A

Structure of Intermediate Filaments
•All intermediate filament family members are elongated proteins with a conserved central α-helical domain.
•The assembled intermediate filament lacks the overall structural polarity (no plus or minus ends)
•Intermediate Filaments do NOT contain a binding site for nucleotide
•Intermediate filament proteins consist of two globular head groups separated by an extended polypeptide chain
•The actual mechanism of assembly and disassembly of intermediate filaments is less understood, compared to actin and microtubules. But it is known that they are regulated by phosphorylation

27
Q

Cytoskeleton proteins-Intermediate Filaments

Give examples of different classes

A
  • Keratin: epithelial cells
  • Vimentin and vimentin-related filaments: connective tissue cells, muscle cells and supporting cells of the nervous system
  • Neurofilament: nerve cells
  • Nuclear lamins: strengthen the nuclear envelope
28
Q

Cytoskeleton proteins-Intermediate Filaments: cellular functions

A

Cellular functions
•The mechanical stability of the plasma- and the nuclear membrane
•Cell-cell interaction

29
Q

Cytoskeleton proteins-Intermediate Filaments: physiological functions

A

Neuron
•Development and regeneration
•Ageing

30
Q

Cytoskeleton proteins-Intermediate Filaments: dysfunctions

A

Progeria (caused by lamin A gene mutation that causes children to age rapidly)

31
Q

What are the different types of cytoskeleton filaments?

A

Actin filaments
Microtubules
Intermediate filaments

32
Q

Advantage of cross linking to create a bundle?

A

Stronger= more resistance to stress

33
Q

What binds to actin?

A

ATP/ADP

34
Q

What are filaments?

A

Long chains of proteins, such as those found in hair, muscle or -flagella.

35
Q

Why are filaments often bundled together?

A

For strength and rigidity

36
Q

What are the proteins that make up the filaments of cytoskeleton?

A
  • Actin filaments
  • Intermediate filaments
  • Microtubules
37
Q

Is Tubulin a globular or fibrous?

A

Globular

38
Q

Is the GTP bound to alpha Tubulin hydrolysed?

A

No

It is needed for structure

39
Q

Is the GTP bound to beta Tubulin hydrolysed?

A

Yes after it is added on to the microtubules

40
Q

Which filaments don’t have plus and minus ends?

A

Intermediate filaments

41
Q

Which filaments dont have binding sites for nucleotides such as ATP?

A

Intermediate filaments

Cell Biology (BY1CB1) (16 decks)

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