<span>It is well known that the centrosome acts as a microtubule organizing center, with its textbook role in forming mitotic spindles in dividing cells. So in many cells, the centrosome with its centrioles is indeed essential to ensure correct cell division, and in these the PCM ensures the distribution of the right number of centrioles to each daughter cell. But there are exceptions – which include somatic cells in fruit flies and some fungi – where no centrioles are needed; and centrosomes in some differentiated cells, including neurons and muscle cells, are inactive.</span>
Large molecules cannot pass through the membrane without help they are too big. This is because the membrane is very selective with what it let enters.
<u>A colony is a territory under the complete political and military control of the settlers of a state, which is distinct from the home territory of the sovereign.</u>
