Centrosome
Non-membrane organelle organizing microtubules and cell division.
The centrosome (Latin centrum 'centre' + Greek sōma 'body'), archaically called the cytocentre, is a non-membrane bounded organelle in animal cells. It serves as the main microtubule organizing centre (MTOC) and a regulator of cell-cycle progression, providing structure for the cell. The centrosome is thought to have evolved only in the metazoan lineage of eukaryotic cells; fungi and plants lack centrosomes and use other structures to organize their microtubules. Although it has a key role in efficient mitosis in animal cells, it is not essential in certain fly and flatworm species.
- composition
- Two centrioles arranged at right angles, surrounded by pericentriolar material (PCM)
- function
- Main microtubule organizing centre (MTOC) and regulator of cell-cycle progression
- associated_with
- Cancer (aberrant numbers linked to tumors)
Lore & Background
Centrosomes are composed of two centrioles arranged at right angles to each other, surrounded by a dense, highly structured mass of proteins termed the pericentriolar material (PCM). The PCM contains proteins responsible for microtubule nucleation and anchoring, including γ-tubulin, pericentrin and ninein. Each centriole is based on a nine-triplet microtubule assembled in a cartwheel structure and contains centrin, cenexin and tektin. In many cell types, the centrosome is replaced by a cilium during cellular differentiation, but once the cell starts to divide, the cilium is replaced again by the centrosome.
Reader's Guide
The centrosome is central to animal cell division and organization. During mitosis, centrosomes migrate to opposite poles of the cell, and the mitotic spindle forms between them. The mother centriole also has a role in making cilia and flagella. The centrosome is copied only once per cell cycle, during S phase, and each daughter cell inherits one centrosome. Aberrant numbers of centrosomes have been associated with cancer. Centrosome alterations in cancer can be structural (e.g., enlarged size due to excess PCM) or numeric (excess centrosomes linked to genome instability). Loss of tumor-suppressor p53 produces superfluous centrosomes, as does deregulation of BRCA1 and BRCA2. The centrosome's evolutionary history shows that centrins, required for centriole duplication, have been present in the common ancestor of eukaryotes but have no recognizable homologs in archaea and bacteria. Some model species like Drosophila melanogaster have lost one centrin subfamily and can develop without centrosomes, relying on functionally redundant machinery.
Did You Know?
- Centrosomes are composed of two centrioles arranged at right angles, surrounded by pericentriolar material containing γ-tubulin, pericentrin, and ninein.
- In non-rodent mammals, the sperm contributes the major part of the centrosome, the centrioles.
Frequently Asked Questions
Who is Centrosome?
Centrosome is a non-membrane-bound organelle found in animal cells that acts as the cell's internal structural hub. It consists of two centrioles positioned at right angles to each other, enveloped in a cloud of pericentriolar material (PCM).
What are Centrosome's powers/role?
Centrosome serves as the primary microtubule organizing center (MTOC), building the cytoskeletal tracks the cell relies on for shape, transport, and chromosome segregation. It also helps pace and regulate the progression of the cell cycle.
Why is Centrosome important?
It provides the structural scaffold that lets animal cells assemble a clean mitotic spindle, ensuring chromosomes are pulled apart accurately during division. Without it, mitosis in animal cells becomes far less efficient and more error-prone.
Does Centrosome appear in every cell type?
No—Centrosome is unique to the metazoan (animal) branch of eukaryotes. Fungi and plants have no centrosome and instead use alternative structures to organize their microtubules, and a few fly and flatworm species can even complete mitosis without one.
What is Centrosome's dark side?
When a cell produces an abnormal number of centrosomes, the resulting mis-segregation of chromosomes can drive genomic instability. This aberrant centrosome count is strongly linked to tumor development in cancer.
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