MCB 150 FINAL EXAM UPDATED ACTUAL QUESTIONS AND CORRECT ANSWERS

MCB 150 FINAL EXAM UPDATED ACTUAL QUESTIONS
AND CORRECT ANSWERS

Question:
1. Structure of Microtubules
Answer:
rigid, hollow tubes made of tubulin

Question:
2. What is tubulin
Answer:
a dimer of alpha-tubulin (GTP) and beta-tubulin (GDP)

Question:
3. How do tubulin dimers form MTS?
Answer:
they polymerize, assemble mt head to tail so mt has polarity

Question:
4. Which end do polymerization and depolymerization happen on MT?
Answer:
possible at both ends, but usually occurs at plus end bc minus end is anchored into centrosome

Question:
5. What happens once there is a dimer addition to a microtubule?
Answer:
GTP in b-tubulin is hydrolyzed and turned into GDP, GTP in a-tubulin is not hydrolyzed for stability

Question:
6. Dynamic instability and GTP cap
Answer:
GTP bound tubulin prevents subunits from peeling away so if polymerization slows down GTP cap is
hydrolyzed and microtubule starts depolymerizing

Question:
7. Tubulin + GTP
Answer:
= polymerization

Question:
8. Tubulin + no GTP
Answer:
= depolymerization

, Question:
9. Does GTP bound tubulin have high or low affinity for tubulin?
Answer:
high

Question:
10. Does GDP bound tubulin have high or low affinity for tubulin?
Answer:
low

Question:
11. Colchicine and Colcemid affect on microtubules
Answer:
Binds tubulin->induces depolymerization->non-specifically affects all microtubules

Question:
12. Vincristine and vinblastine affect on microtubules
Answer:
Binds tubulin->induces depolymerization->targets rapidly dividing cells

Question:
13. Taxol affect on microtubules
Answer:
binds microtubules->stabilizes microtubules->targets rapidly dividing cells

Question:
14. Function of microtubules
Answer:
interphase cell (guiding intracellular transport), dividing cell (segregating chromosomes during mitosis),
ciliated cell (propulsion or sweeping of fluids over membranes)

Question:
15. Where do new microtubules come from?
Answer:
mts originate from the microtubule organizing center (MTOC)

Question:
16. What is major MTOC in animal cells?
Answer:
centrosome (origin and anchor)

Question:
17. What does centrosome contain?
Answer:
pair of centrioles, pericentriolar material