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bis_104_pq_24_ans_fall_08 - to deliver the cargo vesicle(1...

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BIS 104 PQ 24 24. It has been determined that a cargo vesicle can be moved along a MT toward the “plus” end at a speed of ~ 3 micrometers per second (3 um / sec). And, that each individual kinesin motor step covers ~ 8 nanometers (nm). a. How many steps can a kinesin molecule make in one minute? (3 x 10 3 nm / sec) x (1 dimer / 8 nm) x (60 sec / min) = 2.25 x 10 4 steps / min = 375 steps / sec b. A neuron has to transport acetylcholine packaged in a vesicle from near the nucleus, down the axon, to the tip for release at a synapse. The length of the axon is 600 um. Assuming the kinesin motor protein doesn’t stumble and fall off the MT, how many minutes will it take
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Unformatted text preview: to deliver the cargo vesicle? (1 sec / 3 um) x (6 x 10 2 um / 1) x (1 min / 60 sec) = 0.33 x 10 1 min c. What three cellular parameters might influence the rate of cargo movement? Availability of an energy source; one ATP required for each kinesin step. Frictional resistance of the environment; viscosity of cytoplasm and size (bulk) of the cargo d. After kinesin motor proteins and dyneins transport their cargos to one end of a microtubule, how do you suppose these proteins get back to their origin? Kinesins carry dyneins back to the plus end of MTs and dyneins carry kinesins back to the minus ends of MTs....
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