Eukaryotes contain a mother centriole, and a daughter centriole bound together and arranged near the nucleus at right angles. In a cell, they aid in cell division by facilitating the separation of chromosomes, containing DNA, the genetic material of the cell. Centrioles are absent in prokaryotes, red algae, yeast, cone-bearing, and flowering plants, and some non-flagellated or non-ciliated protozoans such as amoebae.
Composition: What are Centrioles Made Of
A centriole is made of nine sets of short microtubule triplets arranged in a cylinder with no central microtubules, making it a hollow center, this arrangement is thus called 9 + 0. Each triplet microtubule consists of a complete microtubule, the A-tubule, on which two additional partial microtubules, the B- and the C-tubules, are assembled. The adjacent microtubules are connected by С-A protein bonds, while the center contains a rod-shaped mass made of proteins, known as the hub. From the hub, develops nine protein strands towards the peripheral triplet microtubules called spokes. This makes the centriole looks like a cartwheel. Deviations from this arrangement are found in Brachyura species, embryos of Drosophila melanogaster, and sperm cells of Caenorhabditis elegans. Centrioles serve as the major microtubule-organizing centers, which is an important event in two major cellular processes: Other Important Roles
