Cytoskeleton Flashcards
What is the order of cytoskletal components in order from largest to smallest?
microtubules, intermediate filaments, actin filaments/microfilaments
Which cytoskeleton component is made of alpha and beta tubulin subunits?
microtubules
What are the subunits of microtubules?
alpha and beta tubulin
Which cytoskeletal component might be involved in the positioning of the nucleus within the cell
microtubules
Which cytoskeletal component might be involved in the mechanical strength of an epithelial cell?
intermediate filaments
Which cytoskeletal component provides the shape of the overall cell structure?
actin/microfilaments
Which statement about the cytoskeleton is not true? A) cytoskeletal component assemble and disassemble often, making them quite dynamic structures B) many cytoskletal components provide movement and mechanical strength for/to a cell C) some cytoskeletal components are composed of many monomeric subunits D) the various components of the cytoskeleton are held together by a mixture of strong ionic and covalent bonds, giving them their characteristic strength
(D) noncovalent bonds hold together the subunits, allowing for the dynamism of the cytoskeleton
The cytoskeleton is a very dynamic structure. What are two benefits/significances of this?
1) small subunits can quickly change cellular position 2) allows for a rapid change in cell morphology (e.g. cell migration)
What are the basic subunits of microfilaments?
globular proteins called G-actin, which polymerize to form actin filaments (F-actin)
Which end of the actin filament has more ability to grow and shrink (more “dynamic”)?
the + end
Platelets change cell shape and form protrusions during blood
clotting. This process involves extensive rearrangement of which cytoskeletal component in particular?
actin filament
T or F: Both microtubules and actin filaments have polarity.
True
What are “MAP’s” in the context of the cytoskelton?
microtubule associated protein- stabilize and organize MT’s
If a cell were to experience a mutation in its microtubules, which of the following functions would you expect to be altered?
A) mitosis
B) cell morphology
C) muscle contraction
D) cellular transportation
E) A and B
F) A, C and D
G) A and D
H) all of the above
(G); all of the other options apply to actin filaments
When you hear “microtubules” what functions should you be thinking of?
Movement (e.g. cell movement, mitosis, organelle orientation, cell trasport)
MT can grow and shrink at both ends. The oscillation between growth and shortening of MT is called _____ .
dynamic instability
Under certain conditions, a filament adds subunits at one
end, and simultaneously loses subunits at the other end. The
net flux of subunits at the two ends is known as
_____.
treadmilling
What is treadmilling, in the context of the cytoskeleton?
when a filament adds subunits at one
end, and simultaneously loses subunits at the other end (gives a movement like appearance)
An absence of catastrophin would most likely lead to which of the following outcomes for microtubules (MT)?
A) stabilization of the MT, resulting in longer, less dynamic MT’s
B) stabilization of the MT, resulting in shorter, more dynamic MT’s
C) destabilization of the MT, resulting in shorter, more dynamic microtubules
D)
destabilization of the MT, resulting in longer, more dynamic microtubules
(C); think: “catastrophin” destabilizes, and destabilization leads to shorter and thus more stable MT’s
Some compounds can disrupt microtubule dynamics and have application in biochemical studies (e.g. anti-cancer drugs). What are 2 examples?
1) cochine- prevents assembly of MT
2) taxol- prevents disassembly of MT
Taxol is a compound that tightly binds to ß-tubulin in assembled microtubulues and prevents disassembly of microtubules. Why might this be a good cancer drug?
MT’s must be able to disassemble for the cell to divide. Therefore, preventing their disassembly could prevent cancer cells from dividing.
What is the MTOC?
microtubule organizing center (centrosome)
In some eukaryotic cells, MTOC’s, in addition to being found in the centrosome, can be found in _____ that are associated with cilium or flagellum
basal bodies