Centrosome: Overview, Structure, Functions, Diagram

The centrosome is an organelle found in animal cells that functions as the cell's microtubule-organising centre. It also helps to regulate the cell cycle. A centrosome consists of two centrioles. Centrosome is a topic of the chapter Cell: The Unit of Life in Biology.

What are Centrosomes?

The centrosome is the structure of the cell that was most accurately identified with the help of these markers. The microtubule organising centre also called the centrosome, is one of the most important structures in the cell; it is responsible for cell shape control, and microtubule orientation to form a proper network and accurate cell division.

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This Story also Contains

1. What are Centrosomes?
2. Structure of Centrosomes
3. Functions of Centrosomes
4. Centrosome Cycle
5. Centrosomes in Different Organisms
6. Centrosome Related Diseases and Disorders
7. Recommended video for Centrosome

It is made up of two centrioles enclosed by a matrix of proteins; the centrosome plays the role of making sure that the chromosomes split properly during mitosis. First identified in the 1800s by Theodor Boveri and Edouard van Beneden, the role of the centrosome in organising the cell and dividing it continues to be seen as crucial to cell biology.

Structure of Centrosomes

The structure of centrosomes is given below:

Centriole Pair

Detailed structure:

A typical centrosome houses two centrioles which are cylindrical structures that have nine microtubule triplets within a cartwheellike formation. These triplets produce a frame for the formation of microtubules and are involved in the process of ciliogenesis and flagellogenesis.

Pericentriolar Material (PCM)

Composition and role:

Around the centrioles, there exists pericentriolar material which is a dense proteinaceous material containing among other components gamma-tubulin, pericentrin, and others. PCM is involved in the nucleation and the anchoring of microtubules since it offers the correct conditions for microtubule elongation.

Centrosome Matrix

Around the centrioles, there exists pericentriolar material which is a dense proteinaceous material containing among other components gamma-tubulin, pericentrin, and others. PCM is involved in the nucleation and the anchoring of microtubules since it offers the correct conditions for microtubule elongation.

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Functions of Centrosomes

The functions of centrosomes are discussed below:

Microtubule Organization

One of the significant components of the PCM is the centrosome matrix from which the cell’s MTOC is derived. It controls the formation and addition of microtubules and maintains the cell integrity, vehicular transport, and sometimes the mitotic spindle of the cells.

Microtubule Nucleation and Anchoring:

The Centrosome is the main MTOC of animal cells organizing the network of microtubules that gives structural support and also plays a role in the transport of particles.

Cell Division

Role in mitosis and meiosis:

Not only that, it initiates the formation of new microtubules, besides organizing and strengthening them in the cell. Similarly, the centrosome also duplicates and sets as the poles of the mitotic spindle that are scattered throughout the chromatids accurately.

Formation of the mitotic spindle:

It also directs the formation of the mitotic spindle: this is a structure that is composed of microtubes and is instrumental in the separation of chromosomes to the daughter cells in mitosis and meiosis.

Cell Cycle Regulation

Centrosome cycle and its coordination with the cell cycle:

Centrosome cycling, which includes duplication and maturation, is well-regulated with another cell cycle so that each daughter cell contains one centrosome to retain the order and functionality of a cell.

Intracellular Transport

Role in the trafficking of vesicles and organelles:

The centrosome helps in the transport of vesicles and organelles within a cell by aligning the tracks formed by microtubules, where molecular motors transport the structures to their required destinations with the help of the tracks, thus assisting in intracellular transport.

Centrosome Cycle

The centrosome cycle is discussed below:

Duplication

Centrosome replication takes place at the beginning of the S phase and results in the duplication of the centrosomes to two by the time the cell begins to divide. This process is controlled strictly by the proteins involved in the cell cycle like cyclins and cyclin-dependent kinases to avoid the mistakes that can cause abnormal cell division and aneuploidy.

Separation

In prophase, the centrosomes that have reproduced start to migrate and position themselves at the poles of the cell. This is spearheaded by motor proteins like the dynein and the kinesin that run along the microtubules. By the end of metaphase, the centrosomes ensure that they are located at the spindle poles where they aid in the formation of the mitotic spindle that enables the segregation of chromosomes.

Function in Cytokinesis

The centrosomes need to be positioned correctly and to function in cytokinesis in which the cells are divided into halves by the breakup of the cytoplasm to create two daughter cells. They assist in the organization of the contractile ring and the cleavage furrow that is required for the proper separation of daughter cells thereby increasing the chances of cell division success.

Centrosomes in Different Organisms

The following describes the centrosome in different organisms:

Animal Cells

The animal cell centrosomes are generally present and include two centrioles surrounded by pericentriolar material (PCM). It is the main microtubule organizing center also known as centrosome and plays a significant role in cell division and organization. It can also manifest itself in different types of cells and at different stages of its development as a result of functional needs.

Plant Cells

Unlike animal cells, plant cells do not contain centrosomes and unipolar spindles of plant cells extend from each pole during cell division. Nonetheless, it involves other microtubule organizing centre (MTOCs) scattered all over the cell. They are centrosomes which are analogous to MTOCs and they help in the organization of microtubules as well as proper cell division The nuclear surface is usually a site of microtubule nucleation during mitosis.

Yeast and Other Eukaryotes

Thus, based on the described characteristics, it is found that yeast cells do not contain centrosomes, whereas their MTOCs are known as the spindle pole bodies (SPBs). Thus, in other eukaryotes, different centrosomes or structurally and functionally similar organelles may be present depending on the organism’s necessities. Such adaptations show how different species provide different solutions to the problems of assembling microtubules and dividing the cell.

Centrosome Related Diseases and Disorders

The disorders are discussed below:

Cancer

Centrosome hyperplasia, the state in which cells contain more than two centrosomes, is manifested in cancer very frequently. It can cause defects in spindle formation, chromosome segregation, and antisepsis which are responsible for tumorigenesis and cancer development.

Microcephaly

The improper regulation of some genes that are involved in centrosome duplication and function also hit human beings leading to microcephaly, a situation where an individual has a small brain. These mutations interfere with cell division and the development of the brain which in turn results in serious neurological complications.

Other Disorders

Abnormality of the centrosome can also underlie other diseases including ciliopathies as well. Centrosomes are involved in the formation and function of cilia and if this structure is affected through defects in proteins associated with the centrosome the functions of cilia are affected leading to diseases like polycystic kidney disease, respiratory diseases, and retinal degeneration.

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