Briefly (one or two sentences) explain why the following statements are either t

Question

Briefly (one or two sentences) explain why the following statements are either true or false.

27. True/False Microfilament treadmilling will be blocked by agents that specifically block ATP
hydrolysis; in contrast these agents will not affect microtubule treadmilling.
28. True/False The centrosome and the gamma tubulin ring complex play key roles in controlling the rate
of catastrophic microtubule disassembly.
29. True/False Nuclear lamina assembly and disassembly is controlled by degrading the nuclear lamins as
cells enter mitosis and rebuilding the nuclear lamina from newly synthesized lamin proteins after mitosis is
finished.

Explanation / Answer

27. True/False Microfilament treadmilling will be blocked by agents that specifically block ATP hydrolysis; in contrast these agents will not affect microtubule treadmilling. FALSE:

Treadmilling results in elongation in the barbed end and shortening in the pointed-end, so that the filament in total moves. Since both processes are energetically favorable, this means force is generated, the energy ultimately coming from the hydrolysis of this molecular unit of energy currrency.

Both processes are affected.


28. True/False The centrosome and the gamma tubulin ring complex play key roles in controlling the rate
of catastrophic microtubule disassembly.

TRUE. The gamma-tubulin ring complex (gammaTuRC) is a protein complex of relative molecular mass approximately 2.2 x 10(6) that nucleates microtubules at the centrosome.  Intracellular acting cytoskeletal assembly and disassembly are tightly regulated by cell signaling mechanisms regulated by actin - all at the centrosome, which holds the process together (or lets it fall apart, as the case may be)

29. True/False Nuclear lamina assembly and disassembly is controlled by degrading the nuclear lamins as
cells enter mitosis and rebuilding the nuclear lamina from newly synthesized lamin proteins after mitosis is
finished.

The nuclear lamina is assembled by interactions of two lamin polypeptides in which the -helical regions are wound around each other to form a two stranded -helical coiled-coil structure, followed by a head-to-tail association of the multiple dimers.

No degrading. Just winding around!

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