Question

6) From the following, what about microtubules is true?

I. Microtubules have structural polarity for bidirectional transport

II. GDP-bound tubulin has a straight conformation

III. Microtubules are crucial for mechanical cellular properties

IV. Protofilaments are composed of tubulin dimers

V. Protofilaments assemble perpendicular to form a fiber

A) II, V

B) I, II, IV

C) I, III, IV

D) I, II, III, IV

E) I, III, IV, V

Answer 1

Ans 6) The correct answer is "C"

Microtubules consists of 2 ends ( + end is fast growing end and - end is slow growing end) and thus bidirectional transport is posisible.They consist of tubulin protein as a heterodimer.13 microtubules constitute 1 protofilament after assembly.Microfilaments impart strength and rigidity to the cell,aids in locomotion etc. GTP-bound tubulin has straight conformation wheras GDP-bound tubulin has curved conformation.