Study Question Sets for Exam
Study Question Set 18 -- Cytoskeleton & Actin - part 1
- Compare (a) intermediate filaments, (b) actin filaments and (c) microtubules
in terms of the general pattern of distribution of each type of cytoskeletal
element in an animal cell.
- What is the general role of "intermediate filaments" in cells?
How did they get this name?
- Explain briefly why the subunit structure of actin filaments (and of microtubules)
allows these cytoskeletal components to behave much more dynamically than
- What are the "+" and "-" ends of actin filaments?
What is the significance of this "+" and "-" polarity
to actin filament polymerization in the cell?
- Describe how ATP hydrolysis after actin addition to an actin filament can
affect filament elongation dynamics.
- Describe the effect that thymosin can have on the state of polymerization
of actin filaments in non-muscle cells.
- Indicate the roles of profilin in facilitating or activating actin filament
- What do we mean by "capping" of actin filaments?
- How does tropomyosin affect actin filament stability?
- How does cofilin affect actin filament stability?
- What is an "Arp"? Where does the name come from?
- How can Arp2/3 lead to formation of actin gels?
- Actin is a "highly conserved" protein. What does this mean? What
types of evolutionary pressures are most probably responsible for this conservation?
- Describe the unit of contraction in striated muscle.
- What do we mean when we say that myosin in a "motor protein" for actin filaments?
- Compare the light chains of myosins II to those of myosins that do not form
- What feature makes myosin II, but not other myosins, able to form filaments?
- Describe the "ATPase cycle" of myosin and relate this cycle to
myosin "motor" activity.
- What is a "minisarcomere"?
- What is its importance to cell phenomena such as cytokinesis (cytoplasmic
division in mitosis)?
- Indicate other situations or locations in which one would find minisarcomeres.
- What are "stress fibers"? What is the relationship between minisarcomeres
and stress fibers?
- Indicate how calmodulin is involved in activating contraction in myosin
II-based systems in non-muscle cells.
study question set
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