front 1 What is the basic structure of a microtubule? | back 1 dimer (beta-tubulin and alpha-tubulin) both hold GTP |
front 2 What does beta-tubulin do that alpha tubulin can't? | back 2 can hydrolyze GTP |
front 3 How many protofilaments does one microtubule have? | back 3 13 - makes a spiral circle |
front 4 Where does most growth and shrinkage occur on a microtubule? Why? | back 4 on the plus end, because the minus end is anchored in the nucleator |
front 5 What does rescue microtubules mean? | back 5 growth - tubulins added |
front 6 what does catastrophe mean? | back 6 Shrinkage |
front 7 What is dynamic instability? | back 7 switching between catastrophe and rescue (same idea as treadmilling) activity only on the plus end bc the minus end is anchored |
front 8 Why do we want dynamic instability? | back 8 to be able to take off and take action by growing or shrinking only on ONE END |
front 9 How do we know when to undergo dynamic instability? | back 9 when the rate of GTP hydrolysis is slower than the rate of tubulin addition |
front 10 What form are dimers added and lost? | back 10 added in GTP form (stable) Lost in the GDP form (less stable) these changes are done by beta-tubulin only |
front 11 What is the structure of the microtubules when GTP bound and GDP bound? | back 11 GTP - straight GDP - bent (trying to change conformation) |
front 12 What are the 2 drugs that destabilize microtubules? | back 12 Colchicine and Nocodozole - favor catastrophe |
front 13 What is the 1 drug that stabilizes microtubules? | back 13 Taxol (cancer therapy) |
front 14 Why would it be bad if cells cant undergo catastrophe on the plus end? | back 14 inhibits cell division - spindle shortens MT by pulling during anaphase, if catastrophe cant occur no depolymerization |
front 15 What are microtubules nucleated by? | back 15 gamma TuRC (ring complex) |
front 16 what end of the microtubule does nucleation occur? | back 16 on the minus end |
front 17 How many gamma TuSC does it take to form a ring complex? | back 17 7 |
front 18 What is the gamma tubulin ration with gamma TuSC and gamma TuRC? | back 18 2 gamma tubulin for every 1 gamma TuSC 7 gamma TuSC for every 1 gamma TuRC |
front 19 what is the total number of protofilaments created? | back 19 14 but we 13 used because one is stacked on top of each other to create the spiral |
front 20 What region does the gamma TuRC perform nucleation? | back 20 MTOC |
front 21 What is the MTOC for animals? | back 21 centrosome |
front 22 What is the centrosome structure? | back 22 has 2 centrioles inside pericentriolar material (jelly) with gamma tubulin rings surrounding (nucleating sites) |
front 23 What is the major function of microtubules | back 23 determine position of the internal organelles centrosome radiates MT in all directions so it can find the center of the cell (puts nucleus in middle and rest of organelles follow position) acts as a highway for transport vesicles to move from one organelle to another |
front 24 How many triplets are centrioles made out of? | back 24 9 one has 13 protofilaments and 2 other couple on and share |
front 25 What are the functions of the different lengths of arms on a microtubule? | back 25 MAP2 - long arms (more stable)- makes sure nothing can touch MT, can only get as close as the length of the arm tau - short arms (less stable) short binding - MT closer to each other |
front 26 why is there a difference between the microtubule protein arms | back 26 MAP - determines spacing - farther (stable binding) tau - closer spacing short binding |
front 27 What are the 2 specific MAPs proteins that affect the rate of polymeriation at the plus end? | back 27 Kinesin-13 = favors catastrophe (destabilization - peels off tubulin dimers) XMAP215 = favors rescue (can pick up dimers and bring them to the plus end to be added) |
front 28 What is the tubulin sequestering proteins and its function? | back 28 stathmin - binds tubulin dimer and keeps it away from the plus end to be added (stops the growth of the plus end) |
front 29 What is the microtubule severing protein? | back 29 katanin - cuts off and chops MT into pieces (can be used to form the spindle in cell division) |
front 30 What are the 2 motor proteins for MT and their function? | back 30 kinesin - walk toward the plus end dysein - walk toward the minus end |
front 31 How does cAMP impact the direction of movement for the kinesin? | back 31 high levels of cAMP activates kinesins to move pigments toward the plus end of the MT to periphery Anteriograde movement through the secretory pathway |
front 32 How does cAMP impact the direction of movement for the dynein? | back 32 low levels of cAMP moves pigments to the minus end of the MT (all clump together in the middle) Retrograde movement |
front 33 What is the mechanism for kinesins? | back 33 1. hold cargo and head binds to B-tubulins on the MT surface (back head ATP front head ADP) 2. the back head is hydrolyzed, releasing inorganic phosphate 3. front head trades and bind ATP tightly and back head swings forward 4. REPEAT |
front 34 How is the dyneins binded to MT? | back 34 MT bound to dynein bound to dynactin complex to the vesicle (cargo) REQUIRES ADAPTER COMPLEX (dynactin) |
front 35 cilia | back 35 movement of fluid, sweeping motion, stays static |
front 36 where could cilia be found | back 36 in lungs (gets rid of fluid and dust), trachea, inner ear (perceive sound) |
front 37 flagella | back 37 cell movement, uses locomotion, like a sperm cell - swims |
front 38 What are cilia and flagella built out of? | back 38 have 9 fold symmetry (9 doublets) with 2 single doublets 9+2 arrangment |
front 39 What causes the flagella to have a whipping movement? | back 39 cross-linking proteins, limit sliding of MT doublets so instead of sliding up the MT bend on one side to another which creates a whipping movement |
front 40 What causes the flagella to have a sliding movement? | back 40 dynein on MT doublets walk along each other either up or down which creates a sliding movement one side is fixed, the other is dynamic |