Lecture 05 Flashcards
Cytoskeletal filament necessary for whole-cell locomotion
Actin filaments
Cytoskeletal filament that provides mechanical strength
Intermediate filaments
Cytoskeletal filament that determines the position of organelles
Microtubules
Cytoskeletal filament that drives the pinching of one cell into two
Actin filaments
Cytoskeletal filament that directs intracellular transport
Microtubules
Microtubules are attached to a single point called _________________.
MTOC - Microtubule Organizing Center
T or F. The centrosome is the MTOC.
True
The centrosome is made up of _________________.
a pair of centrioles
Why are the subunit interactions of the filaments non-covalent?
Rapid assembly and disassembly
During cytokinesis, actin filaments form a ___________ that pinches the cell in two.
contractile ring
T or F. Actin uses GTP for assembly while microtubules use ATP.
False. The other way around
ODD MAN OUT:
Actin, Microtubules, Intermediate filament
Forms a hollow cylinder
Actin
Actin forms a double helix
ODD MAN OUT:
Actin, Microtubules, Intermediate filament
Aids in cell motility
Intermediate filament
ODD MAN OUT:
Actin, Microtubules, Intermediate filament
Strenghtens cellular structure
Microtubules.
Intermediate filaments strengthen the nucleus and overall structural integrity, while actin filaments strengthen the cell cortex and periphery.
Phases of actin assembly
Nucleation, Elongation, Steady State
In which phase of actin assembly does the treadmilling occur?
Steady state (equilibrium phase)
T or F. During elongation, monomers can bind at the pointed end of the actin filament.
True. While monomers preferentially bind to the barbed end, they can still bind reversibly at each end.
The rapid elongation at a filipodia is regulated by which elongation factor?
Formin
Small cross-linking proteins that bind to the parallel actin bundles to strengthen it.
alpha-actinin
Small cross-linking protein : alpha-actinin
Large cross-linking protein : _____________
Filamin
Binding protein that nucleates branching in actin filament
Arp 2/3
What common proteins are found in filopodia?
Formin and alpha-actinin
What common proteins are found in lamellipodia?
Filamin and Arp 2/3
Difference/s and similarity between tropomodulin and capping protein
They both prevent disassembly and assembly of actin.
Tropomodulin = at the pointed end
Capping protein = at the barbed end
T or F. Profilin prevents assembly while thymosin promotes assembly.
False. The other way around.
Accelerates disassembly of actin filament
Cofilin
T or F. ATP is needed to attach myosin to the actin.
False. ATP is needed to release myosin from the actin.
Microtubules are hollow cylindrical structure built from __(a)__ parallel ___(b)___. The (b) are composed of tubulin ________.
13; protofilaments; dimers
Which tubulin monomer is always bound to GTP?
Which tubulin monomer can be bound to GTP or GDP?
a-tubulin; b-tubulin
Differentiate the (-) ends and the (+) ends of actin filaments vs microtubules
In ACTIN FILAMENTS, the (+) end grows more rapidly and the (-) end grows more slowly. In MICROTUBULES, the (+) end GROWS AND SHRINKS more rapidly than the (-) end.
Actin filaments: treadmilling effect
Microtubules: _______________
dynamic instability
Explain dynamic instability
Good job :D
KEYWORDS: Catastrophe & Rescue
Two polymer forms of microtubules
T form - more energy to polymerize
G form - less energy; tends to depolymerize
T or F. The GTP cap is also known as the less stable region of the microtubule.
False. The region with GDP-tubulin dimers is the less stable region.
Actin: Arp 2/3
Microtubule: _______
Augmin. Both nucleates branching.
How does stathmin prevent rescue of microtubles? What protein has the same function in actin filaments?
It binds to subunits to prevent assembly of tubulin dimers. Thymosin.
Motor proteins for vesicular transport.
Kinesin and Dynein
Facilitates anterograde movement (to + end).
Kinesin
Facilitates retrograde movement (to - end)
Dynein
