front 1 Motor proteins are able to generate force by ___________. | back 1 undergoing a series of conformational changes |
front 2 Why does an actin thin filament manage to move continuously during a contraction cycle? | back 2 All of the myosin heads beat out of synchrony with one another. |
front 3 In what form are proteins and neurotransmitters usually transported down the axon of a nerve cell? | back 3 inside transport vesicles |
front 4 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. | back 4 nonprocessive |
front 5 Nucleation of microtubules takes place rapidly inside a cell, where it occurs in association with a variety of specialized structures called _____________. | back 5 All of the provided answers |
front 6 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? | back 6 alpha-helix |
front 7 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? | back 7 Magnesium ions are required for dynein to bind to the A tubules of the axoneme. |
front 8 Which of the following appears to be the most extensible? | back 8 intermediate filaments |
front 9 What would happen if you cultured a frog embryo just after gastrulation in the presence of cytochalasin? | back 9 The cells of the neural plate elongate normally but do not become constricted as usually happens. |
front 10 The cross-bridges that hold intermediate filaments together are composed of _______. | back 10 plectin |
front 11 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. | back 11 ephrin |
front 12 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 _________ | back 12 neural plate |
front 13 Which Microtubule-Organizing Center (MTOC) gives rise to cilia and flagella? | back 13 basal bodies |
front 14 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. | back 14 actin filaments |
front 15 Which of the following appears to be the most extensible? | back 15 intermediate filaments |
front 16 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? | back 16 The axonemes would beat at about half the rate of the intact axoneme |
front 17 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 | back 17 anterograde |
front 18 Which type of cytoskeletal element is described as tough, ropelike fibers composed of a variety of related proteins like keratin? | back 18 intermediate filaments |
front 19 One of the WASP/WAVE family of proteins, specifically WASP, the founding member of the family, is associated with what disease below | back 19 Wiskott-Aldrich syndrome |
front 20 Along which structure do membranous vesicles and organelles typically engage in local movement in the cell periphery of an animal cell? | back 20 microfilaments |
front 21 What is the direct source of energy that powers molecular motors? | back 21 hydrolysis of ATP |
front 22 What motor is associated with microfilaments? | back 22 myosin |
front 23 The first direct measurement of a motor taking single steps was an analysis of ________ stepping using ________. | back 23 kinesin, optical trap technology |
front 24 What happens to the Z lines after contraction of the sarcomere? | back 24 The distance between the Z lines decreases |
front 25 Kinesin movement along a microtubule is said to be highly ________ meaning that it can move considerable distances along an individual microtubule without falling off. | back 25 processive |
front 26 From what structure do cillia and flagella emerge? | back 26 basal bodies |
front 27 What is the minimum number of kinesin heads in contact with a microtubule at all times? | back 27 1 |
front 28 If you were to fix a fish keratocyte and stain it with fluorescent antibodies for myosin II, where would you see the myosin II? | back 28 in a band where the rear of the lamellipodium joins the rest of the cell |
front 29 What protein is responsible for intraflagellar transport of IFT trains back toward the cell body? | back 29 cytoplasmic dynein |
front 30 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? | back 30 EGTA binds to Ca2+ ions, which are known to induce microtubule depolymerization |