16A Assignment Flashcards
Which of the following is not a role of the cytoskeleton?
Provide mechanical strength
Change cell shape
Drive cell movement
Organize organelles
Encode genetic information
(Hopefully, it is obvious. The point is, it is a challenge to think of aspects of cell biology that are not “supported” in some way by the cytoskeleton.)
Encode genetic information
Which cell labeled below experiences wholesale degradation and resynthesis of actin?
A, Mature fibroblast
B, Mitotic Fibroblast
C, Cytokinetic Fibroblast
D, Immature fibroblast
E, None, subunits are reused on a more or less constant basis.
E, None, subunits are reused on a more or less constant basis.
Which of the following has the lowest rate of disassembly/reassembly (also referred to as flux)?
Microfilaments
Intermediate filaments
Microtubules
Intermediate filaments
Which of the following is non-polar?
Microfilament
Intermediate filament
Microtubule
Intermediate filament
Which of the following has the largest cross-sectional diameter?
Microfilament
Intermediate filament
Microtubule
Microtubule
an actin-rich surface area enhancing structure is called:
Hemidesmosome
Basal lamina
Adherens junction
Desmosome
Microvilli
Microvilli
Once a nerve cell establishes a connection to a target cell, enhanced IF assembly is thought to drive up to a five-fold increase in the cell’s _____, which helps to enhance the speed of electrical signals.
length
thickness
volume
striation
thickness
Neurofilament C-terminal extensions are thought to help organize _____ arrays of intermediate filaments.
helical
perpendicular
parallel
tangential
triangular
parallel
Which of the following diseases is associated with defects of the intermediate filament support network?
Muscular dystrophy
Lou Gehrig’s or ALS
Epidermolysis bullosa simplex
Cardiac myopathy
All of the choices
All of the choices
When cells are programmed to die via apoptosis, a specialized set of proteases are activated, whereupon the nucleus begins to lose structural integrity. What do you think might be a major protein family targeted by these proteases?
Keratin
Desmin
Lamin
Neurofilament
Plectin
Lamin
Unlike actin filaments and microtubules, intermediate filaments seem able to have subunits added _____.
at either end
favorably at one end
into the middle
Only at one end
unfavorably at one end
into the middle
Desmosomes are the structures where intermediate filaments (IFs) cross the plasma membrane.
True
False
False
Yes! Although trans-cell IFs sometimes seem to appear in micrographs, looks here are misleading. IFs are contained within a cell boundary. Only proteins associated with the desmosome apparatus (called cadherins) cross the plasma membranes of adjacent cells, thereby imparting great strength to cell-to-cell anchoring between IF networks.
Which of the following is true for all three classes of cytoskeletal elements?
bound specifically by dedicated motor protein
assembled into a polar mature fiber/tube
made of many small protein subunits
NTP hydrolysed in the polymerization cycle
Assembled from the same gene products in all cells
made of many small protein subunits
Yes, all three elements of the cytoskeleton are built from individual subunits that are much much smaller than the mature fiber or tube that results.
