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Unformatted text preview: Answers to the chapter 17 sample questions 1. (A) actin (B) microtubules (C) intermediate filaments 2. c 3. A. actin B. intermediate filaments C. actin D. intermediate filaments E. microtubules F. microtubules G. microtubules H. intermediate filaments I. actin J. actin 4. d 5. d 6. keratin, desmosomes, vimentin, neurofilament, plectin 7. lamins ____ C ____ neurofilaments ____ A ____ vimentins ____ D ____ keratins ____ B ____ 8. Cells should become arrested in mitosis. Normally, the lamins are phosphorylated during mitosis, causing disassembly of the nuclear envelope. At the end of mitosis, the nuclear lamins are dephosphorylated, causing the lamins to reassemble. Inhibition of this last step should therefore prevent the nuclear lamins from reassembling after mitosis. 9. d 10. C, D, A, B, E 11. a 12. beta-tubulin, alpha-tubulin, thirteen, gamma tubulin, centrosome, GTP, basal body, nine, dynein 13. d 14. c 15. A. The newly exposed microtubule plus ends will shrink if you sever the microtubules in the middle. This is because a microtubule grows by adding GTP- carrying subunits to the plus end. The GTP is hydrolyzed over time, leaving only a cap of GTP-carrying subunits at the plus end with the remainder of the tubulin protofilament containing GDP-carrying subunits. Therefore, if you sever a growing microtubule in its middle, you will create a plus end that contains GDP- carrying subunits. The GDP-carrying subunits are less tightly bound than the GTP-carrying...
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- Fall '08