The cytoskeleton is a redesigned fibrous proteinaceous framework found in the cytoplasm of the cell. It provides mechanical support to cells. It also assists the cell in maintaining its own form and movement.
Microtubules are also called tubulin polymers and are larger than the other two. Their diameter is around 25 nanometers. The main function of this fiber is to preserve the shape of cells. It also aids with cell mobility, for instance, the motion of the chromosomes during cell division.
Two centrioles are found in every mammalian cell, and they assist the cell throughout cell division and work throughout the mitosis and meiosis processes. They are observed in some lower plants, including Chlamydomonas, but not in many fungi, angiosperms, the flowering plants and pinophyta, the conifers. They are normally found close to the nucleus, but they are not usually visible when the cell is not dividing.
History: In 1883 and 1888, Edouard van Beneden and Theodor Boveri were the first to spot and recognize the centrioles. In the 1950s, Joseph G. Gall and Etienne de Harven came up with the structure of centriole replication for the first time.
Definition: Centrioles are two barrel-shaped organelles found near the nuclear envelope in the cytoplasm of animal cells. Centrioles assist in the organization of microtubules, which act as the skeletal structure of the cell. They aid in determining the nucleus’ and other organelles’ positions within the cell.
Centriole structure
- It is present in all animal cells. However, it is not found in Amoeba.
- It can be found close but outside the nucleus.
- It has a cylindrical shape at right angles to each other.
- It is approximately 0.5 µm in length and 0.2 µm wide.
- It is devoid of a membrane.
- It has nine sets of triplet tubules on the periphery. Three tubules are positioned at distinct angles in each set.
- They have a 9 + 0 configuration because there are no triplet tubules in the centre.
- It is self-replicating since it contains DNA and RNA.
Function:
- Centrioles play a role in cell division by orienting the mitotic spindle,’ which emerges during cell division.
- Basal bodies are also formed by centrioles. The axonemes of cilia and flagella are formed from these basal structures.
- They aid in the cellular arrangement of microtubules.
- The centrosome’s organization is maintained by centrioles.