Motor proteins are able to generate force by ___________.
undergoing a series of conformational changes
Why does an actin thin filament manage to move continuously during a contraction cycle?
All of the myosin heads beat out of synchrony with one another.
In what form are proteins and neurotransmitters usually transported down the axon of a nerve cell?
inside transport vesicles
A(n) ________ motor, like muscle myosin (myosin II) and unlike myosin V, remains in contact with its track, in this case the thin filament, for only a small portion, less than 5 percent, of the overall cycle.
nonprocessive
Nucleation of microtubules takes place rapidly inside a cell, where it occurs in association with a variety of specialized structures called _____________.
All of the provided answers
The central, rod-shaped domain of an intermediate filament is flanked on each side by globular domains of variable size and sequence. What structure forms the core of the central, rod-shaped domain?
alpha-helix
EDTA is a chemical that binds to and removes (chelates) divalent cations from solution. Treatment of isolated axonemes with EDTA leads to the removal of the inner and outer arms extending from the A microtubules of the axoneme. Which of the following statements wouls appear to be true based on this information?
Magnesium ions are required for dynein to bind to the A tubules of the axoneme.
Which of the following appears to be the most extensible?
intermediate filaments
What would happen if you cultured a frog embryo just after gastrulation in the presence of cytochalasin?
The cells of the neural plate elongate normally but do not become constricted as usually happens.
The cross-bridges that hold intermediate filaments together are composed of _______.
plectin
Which of the following molecules is a non-diffusible, integral protein of the plasma membrane that binds specifically to its receptor on the surface of the growth cone? This protein acts as a neuronal guidance factor.
ephrin
Toward the end of gastrulation in vertebrates, the ectodermal cells situated along the embryo's dorsal surface elongate and form a tall epithelial layer that is called the _________
neural plate
Which Microtubule-Organizing Center (MTOC) gives rise to cilia and flagella?
basal bodies
The focal complexes that form near the leading edge of a motile cell exert traction force through their associated __________ and then typically disassemble as the cell moves forward or mature into larger, more contractile focal adhesions.
actin filaments
Which of the following appears to be the most extensible?
intermediate filaments
Treatment of isolated sperm axonemes with 0.6 M NaCl has been shown to remove selectively the outer arms from the A microtubules of the axoneme, leaving the inner arms in place. What would be the most likely effect on the NaCl-treated axoneme when ATP was added to the medium?
The axonemes would beat at about half the rate of the intact axoneme
Structures that move from the cell body of a neuron down the axon toward the neuron terminals are said to move in a(n) _________ direction. radial
anterograde
Which type of cytoskeletal element is described as tough, ropelike fibers composed of a variety of related proteins like keratin?
intermediate filaments
One of the WASP/WAVE family of proteins, specifically WASP, the founding member of the family, is associated with what disease below
Wiskott-Aldrich syndrome
Along which structure do membranous vesicles and organelles typically engage in local movement in the cell periphery of an animal cell?
microfilaments
What is the direct source of energy that powers molecular motors?
hydrolysis of ATP
What motor is associated with microfilaments?
myosin
The first direct measurement of a motor taking single steps was an analysis of ________ stepping using ________.
kinesin, optical trap technology
What happens to the Z lines after contraction of the sarcomere?
The distance between the Z lines decreases
Kinesin movement along a microtubule is said to be highly ________ meaning that it can move considerable distances along an individual microtubule without falling off.
processive
From what structure do cillia and flagella emerge?
basal bodies
What is the minimum number of kinesin heads in contact with a microtubule at all times?
1
If you were to fix a fish keratocyte and stain it with fluorescent antibodies for myosin II, where would you see the myosin II?
in a band where the rear of the lamellipodium joins the rest of the cell
What protein is responsible for intraflagellar transport of IFT trains back toward the cell body?
cytoplasmic dynein
Which of the following is a plausible explanation for the fact that the chemical EGTA [ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid; also known as egtazic acid] blocks microtubule disassembly?
EGTA binds to Ca2+ ions, which are known to induce microtubule depolymerization