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39 Cards in this Set

  • Front
  • Back
what are the 3 major cytoskeleton elements?
1) actin
2) microtubules
3) intermediate filaments
F-actin is a polymer version of which type of actin?
Globular actin (G-actin)
what is the approximate diameter of actin filaments?
what are the two major ways actin is used in the cell?
1) cellular motility
2) strucutal scaffolding
what occurs at the + and - ends of actin filaments during steady state?
units of G-actin are added at the + end and lost at an equal rate at the - end
of what is a microfilament of actin composed?
2 fibers of F-actin which are wound around each other.
via which 2 molecule classes do actin filaments participate in cell-cell interactions and cell-substrate interactions, respectively?
cell adhesion molecules; integrins
what is the role of cytochalasins?
they disrupt actin filament polymerization, allowing scientists to study the roles actin plays in the cell.
what is phalloidin? what impact does it have on polymerization?
a drug which stabilizes F-actin; it prevents depolymerization
microtubules are composed of heterodimers of which molecules?
alpha and beta tubulin
how big are the filaments of microtubules?
how many protofilaments, composed of heterodimers, are in one microtubule?
13 protofilaments
where is the microtubule organizing center (MTOC) located?
in the centrosome
do microtubules play motility roles in the cell in addition to their structural roles?
kinesin and dynein are part of which class of proteins?
microtubule-associated proteins (MAPs)
does kinesin bring material toward the + or - end of microtubules? dynein
kinesin brings material toward the + end (out of the cell) and dynein brings material toward the - end (into the cell)
what is the microtubule analog for phalloidin? for cytochalasins?
Taxol; colchicine
how thick are intermediate filaments?
approximately 10nm
what is the primary role, structural or motility, of intermediate filaments?
why don't intermediate filaments exhibit polarity?
because they are stacked in an antiparallel fashion
where in the structure do intermediate filaments exhibit the greatest level of diversity?
at the C- and N- termini
is ATP hydrolysis necessary for polymerization of depolymerization of actin filaments?
which microfilament plays an important role in forming contractile ring during telophase?
which two types of cellular "feet" do actin filaments compose?
filopodia and lamellipodia
why do molecules at the - end of microfilaments fall off more quickly than those at the + end?
because they are bound to ADP instead of ATP. (bound ADP promotes depolymerization)
what class of proteins help actin to form a structural scaffolding network?
actin binding proteins
which proteins are essential in anchoring actin filaments?
which element of cytoskeleton is most intimately involved in shaping the cell membranes and is consequently found in large amounts below membrane surface?
which are hollow, actin, intermediate filaments, or microtubules?
at which end of microtubules does most polymerization take place? depolymerization?
both take place at + end because - end is anchored
is microtubule depolymerization and polymerization controlled by ATP or GTP hydrolysis?
which occurs more quickly in a growing microtubule, GTP hydrolyis or polymerization
when GDP is present, which process is more favorable, polymerization or depolymerization?
what is the term used when a microtubule filament switches from growth to shrinking?
how many centrioles compose a centrosome?
which type of tubublin binds microtubules to the centrosome?
gamma tubulin
what is the energy source for kinesin and dynein?
is dynein transport typically anterograde or retrograde? kinesin transport?
retrograde; anterograde
name 6 different intermediate filaments and their locations.
1) Keratins (epithelia)
2) Vimentins (CT, mesenchyme)
3) Desmin (skeletal muscle)
4) Glial Fibrillary Acid Protein (Glial cells)
5) Neurofilaments (neurons)
6) Lamins (nucleus of all cells)