Term
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Definition
| Calcium and ATP stimulate the adjacent microtubule doublets slide with respect to one another, causing the axoneme to bend and the cilia to beat in a rhythmic motion. |
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Term
| Name and describe the chief feature of the internal structure of a cilium. |
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Definition
| The axoneme, a bundle of microtubules and their associated proteins that extends from the base to the tip of the cilium. |
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Term
| What is the distinct pattern of cilium structure called? |
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Definition
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Term
| To what does the axoneme attach to the interior of the cell? |
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Definition
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Term
| What is the same about an axoneme and its corresponding basal body? |
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Definition
| Same outer diameter, same nine-fold symmetry. |
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Term
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Definition
| Nine outer doublet microtubules surrounding two central microtubules. |
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Term
| Describe the structure of a basal body? |
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Definition
| nine fused triplet microtubules surrounding a hollow core |
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Term
| What protein makes up microtubles? |
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Definition
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Term
| What are the other two filamentous proteins discussed? |
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Definition
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Term
| What organism was the subject of study for the deciliation procedure, and why? |
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Definition
| Tetrahymena, because they have the ability to regenerate its cilia. |
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Term
| How do colchicine and colcemid function? |
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Definition
| They inhibit the addition of tubulin monomers to growing microtubules. |
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Term
| Which drug(s) that affect(s) microtubule assembly inhibits the addition of tubulin monomers to growing microtubules? |
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Definition
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Term
| What affect does taxol have? |
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Definition
| It prevents the cycling of monomers by stabilizing the microtubules and thus using up free tubulin in the cytoplasmic pool. |
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Term
| Which drug(s) that affect(s) microtubule assembly prevent(s) the cycling of monomers by stabilizing the microtubules and thus using up free tubulin in the cytoplasmic pool |
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Definition
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Term
| What function does cyclohexamide have? |
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Definition
| It inhibits cellular protein synthesis by blocking ribosomal translocation along the mRNA. |
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Term
| Which drug(s) that affect(s) microtubule assembly by blocking ribosomal translocation along the mRNA? |
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Definition
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Term
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Definition
A - radial spoke B - nexin link C - B-tubule (outer doublet) D - A-tubule (outer doublet) E - outer dynein arm F - inner dynein arm G - central tubule H - central/inner sheath I - plasma membrane |
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Term
| Approximately how long does reciliation take? |
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Definition
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Term
| What is the main feature of the deciliation medium that drives the deciliation procedure. |
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Definition
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Term
| How did we assay for motility? |
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Definition
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Term
| what is the most reliable scoring method for determining the number of motile cells? |
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Definition
| % motility = 100(#motile)/(#total) = % motile cells at time t |
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Term
| What is the next best approach for determining the amount of motile/nonmotile cells? |
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Definition
| % nonmotile = 100(#now/#original) = % nonmotile cells at time t; to find the number of motile, subtract that percentage from 100 |
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Term
| What is the main disadvantage of using the secondary equation for determining motility? |
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Definition
| It relies on much more accurate sampling of the regenerating cells at each time point. |
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Term
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Definition
| It is an estimate of the time at which 50% of the cells are motile, and is a measure of the rate of regeneration (higher value, slower regen) |
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Term
| What should a graph of motility show? |
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Definition
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Term
| What information should we gather from tube 1? (control: no inhibitor added) |
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Definition
| Classic reciliation should occur with a sharp rise in motility between 60-90 minutes. |
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Term
| What information should we gather from tube 2? (cyclohexamide added and not removed) |
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Definition
| There is only about a 20% gain in motility. this little amount was due to the reserve proteins that the cell used to assemble cilia, showing that cyclohexamide inhibits protein synthesis but does nothing to existing proteins) |
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Term
| What information should we gather from tube 3? (cyclohexamide added and removed after 30 minutes) |
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Definition
| Shows cyclohexamide is reversible, and graph shows a 30 minute delay to tube 1 (control) corresponding to the time inhibitor was present |
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Term
| What information should we gather from tube 4? (colchicine added and not removed) |
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Definition
| Shifts equilibrium towards heterodimers by binding to alpha tubulin, motility gets worse. |
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Term
| What information should we gather from tube 5? (Colchicine added and then removed) |
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Definition
| Reversible - 30 min shift in regen. |
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Term
| What information should we gather from tube 6? (Caffeine added and not removed) |
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Definition
| roughly 90 minute delay in motility increase; this inhibitor was never washed off, but cell was able to counter the effects of caffeine and adjusted: recognition of high cAMP levels, downregulates adenylyl cyclase and upregulates phosphodiesterase to eventually shift to the correct levels; takes awhile (90 min) |
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Term
| How does GTP bind to alpha tubulin? |
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Definition
| stabily - does not cleave/hydrolyze the bond |
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Term
| How does GTP bind to beta tubulin? |
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Definition
| unstabily - hydrolyzes the GTP to harness energy and use for microtubule assembly |
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Term
| Are alpha and beta tubulin different proteins? |
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Definition
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Term
| Which tubulin protein does colchicine bind to? |
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Definition
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Term
| Which end of the tubulin monomers binds MAPs and Calcium? |
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Definition
|
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Term
| how do alpha and beta tubulin combine? |
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Definition
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Term
| How do microtubules and heterodimers interact? |
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Definition
| they exist in a dynamic equilibrium |
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Term
| what type of equilibrium is there between alpha and beta tubulin and their associated heterodimers |
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Definition
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Term
| How many protofilaments does a microtubule contain? |
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Definition
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Term
| How do protofilaments form? |
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Definition
| heterodimers link end to end to make a protofilament, packing together in a helical arrangement |
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Term
| where do microtubule doublets occur? |
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Definition
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Term
| Where do microtubule triplets occur? |
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Definition
| basal bodies and centrioles |
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Term
| Describe a microtubule doublet. |
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Definition
| Begin with 13 protofilaments for the A subtubule, and add on 10 more to make a B subtubule. |
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Term
| Describe a triplet microtubule. |
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Definition
| Begin with 13 protofilaments for the A subtubule, add on 10 more to make a B subtubule, add on 10 more to make a C subtubule. |
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Term
| What does warming do to the dynamic microtubule equilibriium? |
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Definition
| shifts towards microtubules |
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Term
| What does the addition of colchicine do to microtubule equilibrium? |
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Definition
| shifts towards heterodimers |
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Term
| What does low pressure do to microtubule equilibrium? |
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Definition
| shifts towards microtubules |
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Term
| Describe microtubule polarity. |
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Definition
| heterodimers add to the plus end, and dissociate from the minus end (treadmilling) |
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Term
| What is the motor protein for the axoneme? |
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Definition
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Term
| How do the nexin links connect doublets? |
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Definition
| Attach the A subtubule to the B subtubule of the adjacent doublet. |
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Term
| Where do the poles of the axoneme lie? |
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Definition
| The plus end lies towards the tip of the cilium, the minus end lies towards the base. |
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Term
| What is the function of GTP? |
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Definition
| it is hydrolized by beta tubulin during assembly and provides the energy needed for microtubule assembly |
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