Centrioles and Centrosomes – The Simple Cell – Part 11
In Part 3 of this series on the Simple Cell, Things Just Don’t Float Around, we discussed the cytoskeleton of the cell. One of the structures mentioned was the centrosome, however it was never discussed in any detail. Today we are going to examine the centrosome.
There is a region of the cell that lies near the center and close to the nucleus. In this region there exists 2 barrel shaped structures called the centrioles. Each centriole is made up of nine bundles of three microtubules. This region of the cell contains not only the centrioles, but it also has a very thick and protein ladened mass of material known as the pericentriolar material. Altogether they make up the centrosome.
The centrosome and centriole have a number of functions within the cell and those functions are;
- Cell Organization – The centriole is responsible for the organization and alignment of the microtubules throughout the cell. Part of that alignment involves the location of the nucleus within the cell.
- Cilia and Flagella – The original centriole, often referred to as the mother centriole, controls the positioning of cilia and flagella (we will discuss them in more detail in the next installment) and will establish themselves as the basal body of them. It has been discovered that several genetic disorders have been associated with the cell’s failure to produce working cilia and flagella with the help of the centrioles.
- Mammalian Embryonic Development – During the embryonic development of mammals, the centriole is responsible for the proper alignment of the cilia toward the posterior section of the embryonic node cells. This alignment is critical to the asymmetric left-right development of the embryo.
- Cell Division – When cell division begins, the centrioles replicate themselves. Once replicated, each pair of centrioles begin to move to opposite ends of the cell. As the centrioles move away from each other, they form small thread-like microtubules known as the mitotic spindles. The mitotic spindles attach to the chromosomes and pull the replicated set away from the original set of chromosomes. The two sets of chromosomes are pulled by the mitotic spindles into the newly divided daughter cells.
Tiny structures with huge functions, the centrioles and centrosomes are important structures within the cell. Yet I wonder how the first eukaryotic cells divided and replicated themselves before the centrioles and centrosomes evolved? Once again we see the impossibility of evolution and the magnificent handiwork of our Creator God.