| MadSci Network: Cell Biology |
Cilia and flagella are projections from the cell. They are made up of microtubules . They are motile and designedeither to move the cell itself or to move substances over or around the cell. The primary purpose of cilia in mammalian cells is to move fluid,mucous, or cells over their surface. Cilia and flagella have the same internal structure. The major difference is in their length.
Cilia and flagella are organized from centrioles that move to the cell periphery. These are called "basal bodies" Basal bodies control the direction of movement of the cilia.
Like Cilia and Flagella, Centrioles are also made of microtubules. The difference is that they contain 9 sets of triplets and no doublet in the center.How the triplets in the basal body turn into the cilium doublet remains a mystery.Centrioles come in pairs, each organized at right angles to the other.Centrioles organize the spindle apparatus on which the chromosomes move during mitosis.
Centrioles replicate autonomously like mitochondria and peroxisomes. They begin from centers which contain proteins needed for their formation (tubulin, etc.), Then the procentrioles form. Each grows out a single microtubule from which the triplet can form. Once a centriole is made, daughter centrioles can grow out from the tubules at right angles a. These then add to the daughter cell (in a dividing cell), or they move to the periphery and form the basal body for the cilium.
----adapted from http://cellbio.utmb.edu/cellbio/cilia.htm
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