For each of the following sentences, fill in the blanks with…

Fоr eаch оf the fоllowing sentences, fill in the blаnks with the best word or phrаse selected from the list below. Not all words or phrases will be used; use each word or phrase only once. Microtubules are formed from tubulin [1]. Tubulin subunits are stacked together into protofilaments; thirteen parallel protofilaments form the [2] structure of a microtubule. Therefore the structures of the two ends of the microtubule are [3]. [4] ring complexes are important for microtubule nucleation and are concentrated in the [5]. A microtubule that is quickly growing will have a string of [6] tubulins that helps prevent the loss of subunits from its growing end. The motor protein [7] generates the bending motion in cilia.