Term
| How do flagella propel cells? |
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Definition
| using repetitive wavelike motion |
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Term
| Explain the ultrastructure that cilia and flagellum have in common |
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Definition
-a core of microtubules sheathed by the plasma membrane
- a basal body that anchors the cilium or flagellum
- a motor protein called dynein |
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Term
| What doe the motor protein dynein do? |
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Definition
| drives the bending movement of the cilium or flagellum |
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Term
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Definition
| Microtubules in a cilium or flagellum are arranged in a 9+2 array. the nine outer microtubules carry two rows of dynein molecules |
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Term
| How does dynein cause movement in microtubule doublets? |
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Definition
the dynein arms of one microtubule doublet grip the adjacent doublet, push it up, release, and then grip again.
If the two microtubule doublets were not attached, they would slide relative to each other
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Term
| Explain how dynein causes movement in normal cilium and flagellum |
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Definition
| two adjacent doublets cannot slide far because they are physically restrained by proteins so they bend |
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Term
| What is the structural role of microfilaments? |
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Definition
| to bear tension and resist pulling forces within the cell |
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Term
What is the 3-D network called that is created by Microfilaments?
where is it and what does it do? |
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Definition
the cortex
it is just inside the plasma membrane
it helps support the cell's shape |
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Term
| Microfilaments that function in cell motility contain a protein other than actin. What is it? |
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Definition
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Term
| What is amoeboid movement? |
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Definition
| Amoeboid movement is a crawling-like type of movement accomplished by protrusion of microfilaments in the cytoplasm of the cell involving the formation of pseudopodia. The cytoplasm slides and forms a pseudopodium in front to move the cell forward. |
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Term
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Definition
(cellular extensions)
extend and contract through reversible assembly and contraction of actin subunits into microfilaments |
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Term
| How do the bundles of long fibers run in skeletal muscles? |
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Definition
| they run parallel to the length of the muscle |
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Term
| What does a muscle fiber contain? |
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Definition
| bundles of smaller myofibrils arranged longitudinally |
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Term
| What is a vertebrate skeletal muscle characterized by? |
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Definition
| a hierarchy of smaller and smaller units |
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Term
| What type of filaments are myofibrils composed of? |
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Definition
thin filaments (2 strands of actin, one strand of regulatory)
Thick filaments (staggered arrays of myosin molecules) |
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Term
| What is another name for striated muscle? |
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Definition
|
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Term
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Definition
| the contractile unit of a myofibril; sarcomeres are repeating units, delimited by the Z bands along the length of the myofibril. |
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Term
| What borders the sarcomeres? |
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Definition
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Term
| What do the myofilaments contain? |
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Definition
| I band, A band and H zone |
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Term
| When the filaments slide past each other longitudinally, what happens? |
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Definition
| the I bands and H zone shrink |
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Term
| What causes the sliding of the filaments? |
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Definition
–interaction between the actin and myosin molecules of the thick and thin filaments
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Term
| When is the only time a muscle fiber will contract? |
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Definition
| only when stimulated by a motor neuron |
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Term
|
When a muscle is at rest the myosin-binding sites on the thin filament are blocked by the regulatory protein ____.
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Definition
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Term
| What causes the myosin-binding sites to be uncovered |
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Definition
| Calcium ions (Ca2+) bind to another set of regulatory proteins, the troponin complex |
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