Centriole is a structure found in eukaryotic animal cells. Plant cells and fungi do no contain centrioles. Centriole is the part of the cell, which acts as the center for producing microtubules, which are the component of cytoskeleton. Cytoskeleton is the skeleton of the cell that provides both shape and structure to a cell. Animal cells contain 2 centrioles, which together form the structure, centrosome. In other words, the centrioles are found within the centrosomes, which is a small region in the cytoplasm near the nucleus. Within the centrosomes, the two centrioles are positioned in such a way that both are perpendicular to each other. Like other structures of a cell, centrioles too perform several important functions. Below here is a brief discussion about the centriole function and structure in the study of biology.
Structure of the Centriole
Centriole is a cylindrical or barrel shaped structure that can be found lying adjacent to the nucleus. It basically consists of microtubules. Each centriole consists of nine microtubules. Both the centrioles are found in pairs, and they are positioned at an right angles to one another. At the time of cell division, both the centrioles move in the opposite direction towards the poles or ends of the nucleus. Centrioles become evident only at the time of cell division. At other times, one can see only the centrosome as a darker area of the cytoplasm.
What is the Function of the Centriole?
Centriole plays a crucial role at the time of cell division. At the time of cell division, centrioles replicate to form two centrosomes, each with two centrioles. The two centrosomes then move in the opposite direction towards the opposite ends of the nucleus. From each centrosome, some thread like microtubules appear, which are known as spindle or mitotic spindle. During cell division, the single parent cell divides itself into two daughter cells, and the spindle is responsible for separating or pulling the replicated chromosomes to the two daughter cells. So, centrioles helps in the organization of the mitotic spindle, as well as the completion of cytokinesis.
Centrioles as a part of centrosome also play a significant role in cellular organization, especially in organizing the microtubules in the cytoplasm and the spatial arrangement of the cell. Even the position of the nucleus is determined by the position of the centrioles. The mother centriole (the original or older centriole, from which a new centriole develops during cell division) determines the position of cilia and flagella in the organisms with these organelles. In fact, the mother centriole become the basal body in these organisms. A failure of the cell to make functional cilia and flagella with the help of centrioles has been found to be associated with several developmental and genetic diseases. Another important fact about centriole functions is that during mammalian development, proper orientation of cilia via centriole positioning toward the posterior of embryonic node cells is considered as quite crucial for the establishment of left-right asymmetry.
So, these are the main centriole functions in animal cells. Centrioles take part in several important functions like, organization of the microtubules and formation of cilia and flagella. It is also involved in determining the position of the nucleus. Earlier, it was thought that centrioles were essential for the formation of mitotic spindle. But recent experiments in this regard have revealed that cells whose centrioles have been removed can too progress through the G1 stage of inter-phase (stage in which the cell grows and increases in mass to prepare for cell division, prior to DNA synthesis) before both the centrioles can be synthesized. Even mutant flies without centriole can be found to develop normally. However, such adult flies could not develop cilia and flagella, which once again emphasizes the importance of centrioles in the formation of these organelles.