BIOL 4100 EXAM 4 QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS VERIFIED
cytoskeleton
collection of multiple types of protein filaments that provide shape, support, movement,
and intercellular transport
The cytoskeleton is highly organized but is also
dynamic
The cytoskeleton is dynamic. What does this mean?
it can be assembled, disassembled, and reassembled
intermediate filaments
ropelike fibers with a diameter of about 10nm and are made of fibrous intermediate
filament proteins
microtubules
hollow cylinders made of the protein tubulin; they are long and straight and typically
have one end attached to a single molecule-organizing site called a centrosome
actin filaments
helical polymers of the protein actin; flexible structures that are organized into a variety
of linear bundles, two-dimensional networks, and three-dimensional gels
The subunits of intermediate filaments have _________
long 'rod' shaped domain of a-helix and unstructured heads, which allows simple
dimerization with one another
In intermediate filaments, antiparallel dimers result in
,identical ends that interact with the next octamer, and these interactions are non-
covalent
Which type of filament is abundant in cells that experience mechanical forces
(like nerve cell axons, muscle cells, and epithelial cells)?
Intermediate filaments
Why are intermediate filaments abundant in cells that experience mechanical
forces?
this prevents tearing of cells and membranes (like reinforcing concrete)
Intermediate filaments in each cell are indirectly connected to those of
neighboring cells through the __________
desmosomes, which establishes a continuous mechanical link from cell to cell
throughout the epithelial sheet
What are the four classes of intermediate filaments?
1) keratin filaments
2) vimentin and vimentin-related filaments
3) neurofilaments
4) nuclear lamins
keratin filaments are found where?
in epithelial cells
Where are vimentin and vimentin-related filaments found?
in connective-tissue cells, muscle cells, and glial cells
Where are neurofilaments found?
in nerve cells
, Where are nuclear lamins found?
in all animal cells
What is the purpose of nuclear lamins?
to provide strength to the nuclear envelope and make sure that is stays its correct
shape
Intermediate filaments strengthen cells against ________
mechanical stress
Every kind of epithelial cells has a distinct keratin filament composed of
_________
a mixture of keratin subunits
Keratin filaments--filament network
Filament network reaches across the cells, and are connected to desmosomes (cell-to-
cell contacts), which help to distribute stress of stretching
Mutations in keratin result in
cells that are highly sensitive to shear force (for example, epidermolysis bullosa
simplex, which means the person is susceptible to mechanical injury)
Improper accumulation of ________ causes ALS or Lou Gehrig's disease
neurofilaments
Nuclear lamina is less rope-like, and more _________
mesh-like
What is the function of nuclear lamina?
-provides support and protection for the nucleus
-provides places for chromosome tethering
COMPLETE SOLUTIONS VERIFIED
cytoskeleton
collection of multiple types of protein filaments that provide shape, support, movement,
and intercellular transport
The cytoskeleton is highly organized but is also
dynamic
The cytoskeleton is dynamic. What does this mean?
it can be assembled, disassembled, and reassembled
intermediate filaments
ropelike fibers with a diameter of about 10nm and are made of fibrous intermediate
filament proteins
microtubules
hollow cylinders made of the protein tubulin; they are long and straight and typically
have one end attached to a single molecule-organizing site called a centrosome
actin filaments
helical polymers of the protein actin; flexible structures that are organized into a variety
of linear bundles, two-dimensional networks, and three-dimensional gels
The subunits of intermediate filaments have _________
long 'rod' shaped domain of a-helix and unstructured heads, which allows simple
dimerization with one another
In intermediate filaments, antiparallel dimers result in
,identical ends that interact with the next octamer, and these interactions are non-
covalent
Which type of filament is abundant in cells that experience mechanical forces
(like nerve cell axons, muscle cells, and epithelial cells)?
Intermediate filaments
Why are intermediate filaments abundant in cells that experience mechanical
forces?
this prevents tearing of cells and membranes (like reinforcing concrete)
Intermediate filaments in each cell are indirectly connected to those of
neighboring cells through the __________
desmosomes, which establishes a continuous mechanical link from cell to cell
throughout the epithelial sheet
What are the four classes of intermediate filaments?
1) keratin filaments
2) vimentin and vimentin-related filaments
3) neurofilaments
4) nuclear lamins
keratin filaments are found where?
in epithelial cells
Where are vimentin and vimentin-related filaments found?
in connective-tissue cells, muscle cells, and glial cells
Where are neurofilaments found?
in nerve cells
, Where are nuclear lamins found?
in all animal cells
What is the purpose of nuclear lamins?
to provide strength to the nuclear envelope and make sure that is stays its correct
shape
Intermediate filaments strengthen cells against ________
mechanical stress
Every kind of epithelial cells has a distinct keratin filament composed of
_________
a mixture of keratin subunits
Keratin filaments--filament network
Filament network reaches across the cells, and are connected to desmosomes (cell-to-
cell contacts), which help to distribute stress of stretching
Mutations in keratin result in
cells that are highly sensitive to shear force (for example, epidermolysis bullosa
simplex, which means the person is susceptible to mechanical injury)
Improper accumulation of ________ causes ALS or Lou Gehrig's disease
neurofilaments
Nuclear lamina is less rope-like, and more _________
mesh-like
What is the function of nuclear lamina?
-provides support and protection for the nucleus
-provides places for chromosome tethering
