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SI session Nov. 29 Ch. 16 answers

SI session Nov. 29 Ch. 16 answers - Kaiser Imam BIOL 215 SI...

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Kaiser Imam November 29, 2007 BIOL 215 SI Session Chapter 16 Chapter 16: Cellular Movement 1. __ Motor proteins or mechanoenzymes __ are enzymes that interact with cytoskeletal proteins to produce motion at the molecular level. The combined effect of these molecular motions is to produce motion at the __ cellular __ level. 2. Motor proteins are powered by __ hydrolysis of ATP __. 3. In eukaryotes, components of the cytoskeleton that can interact with motor proteins include __ microtubules __ and __ microfilaments __. 4. Motor proteins that interact with microtubules are called __ microtubule-associated motor proteins (motor MAPs) __. These are usually involved in transporting __ vesicles __ or __ organelles __ along a microtubule track. 5. Classes of motor proteins that are associated with microtubules include __ kinesins __ and __ dyneins __. 6. Motor proteins move in __ one __ direction(s) along their cytoskeletal tracks. 7. __ Dyneins __ move their cargo toward the minus end of the microtubule. 8. __ Kinesins __ move their cargo toward the plus end of the microtubule. 9. “Inbound” traffic to the center of the cell requires motor MAPs moving toward the __ minus __ end of microtubules. 10. “Outbound” traffic to the periphery of the cell uses motor MAPs that move toward the __ plus __ end of microtubules. 11. Microfilament-associated motor proteins include the __ myosins __. 12. Motor MAPs exhibit __ processivity __, meaning they can travel long distances before detaching from the microtubule. 13. What are some of the activities involved in cellular motility? How is motility related to contractility? Motility involves motor proteins interacting with cytoskeletal components to produce movement in the cell. Motility includes the movement of a cell (or a whole organism) through its environment, the movement of the environment past or through the cell, transport 1
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of components within the cell, or the shortening of the cell itself. Contractility is a related concept which involves the shortening of muscle cells. 14. Describe how motor MAPs are used in the axons of neurons. Motor MAPs were first studied in the context of transporting materials within a neuron. A neuron consists of a cell body with a long axon extending from it. At the end of an axon is a terminal called the synaptic knob, where neurotransmitters are released into the synapse. Ribosomes are only found in the cell body, so no protein synthesis occurs in the axon or synaptic knobs. Therefore, neurotransmitters synthesized in the cell body must be transported to the synaptic knobs before they can be released. These neurotransmitters are packaged into vesicles in the cell body and are transported along microtubules extending the length of the axon. Kinesins would be used in this case because the vesicles are being moved away from the cell body toward the plus end of microtubules. Keep in mind that proteins can be returned to the cell body using dyneins. This process as a whole is called fast axonal transport.
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