Plants are eukaryotic organisms that are made up of millions of cells. Every cell has a definite nucleus, a cell wall, and a lot of different organelles. Some of these organelles set plant cells apart from animal cells. On the other hand, there are some organelles that are only found in animal cells, and plant cells usually lack these organelles.
Centrosomes are one of the most important organelles in a cell. But do plant cells have centrosomes? Or is it just exclusive to animal cells?
Keep reading to find out everything about this unique organelle and whether plant cells possess this organelle.
What is a centrosome, and what does it do?
A centrosome is a cytoplasmic organelle of a cell that resides in close proximity to the nucleus. During cell division, this organelle moves to the opposite poles of the cell to form a structure called the mitotic spindle. Centrosome plays an active role in mitosis cell division and influences the advancement of the cell cycle. Besides, it also has a positive effect on accumulating microtubules. By organizing microtubules, centrosomes play a role in coordinating the motility and adhesion within cells.
Centrosome also has active responsibilities in conducting embryogenesis and locomotion within the cell. Cell division cannot proceed completely without the help of a centrosome. It has distinct roles in each phase of the cell cycle.
On the other hand, an uncontrolled number of centrosomes in the cell may precipitate an abnormal cell division, leading to production of cancer cells. This is why centrosomes have a crucial role in the cell cycle. Irregularity in centrosome number and function also causes genomic instability to some extent.
Are Centrosomes Present in Plant Cells?
Although centrosomes are important organelles for cell division, they are only found in animal cells. Plant cells lack centrosomes, but they can take part in cell division in a different way.
Although there are no centrosomes in plant cells, the spindle formation in plants takes place through the microtubules arranged by the rigid cell wall. The microtubule organizing region in plant cells undergoes polarization in the metaphase stage of cell division. In this way, cell division is actively conducted in plant cells even without the help of centrosomes.
Besides, there are specific enzymes within the plant cells that are responsible for the separation of the chromosomes during the anaphase stage of mitosis cell division. The combination of microtubule-organizing regions and these specific enzymes makes cell division take place smoothly despite lacking centrosomes or centrioles in plant cells.
Motor proteins like γ-tubulin ring complex in plants also facilitate the cell division process in plants by allowing the formation of microtubules in different regions. In the absence of centrosomes, directional mitosis takes place in plants through the reorganization of microtubules. Besides, actin filaments and phragmoplast of microtubules also play a role in the progression of cell cycle and cell division in plants.
With so many interesting features, plant cells face no difficulty in taking part in cell division.
What is its role in cell division?
The centrosome is a non-membrane bound organelle that has an important role in cell division. Especially in animal cells, cell division may fail to exist without the presence of centrosomes. Animal cells do not possess protein complexes or self-organizing microtubules like plants to facilitate cell division. So, animal cells have to depend solely on centrosomes to execute cell division smoothly.
The main role of the centrosome is to help in the formation of the mitotic spindle that plays an active function in mitosis cell division. It also helps to maintain the constant chromosome number during cell division.
Besides, centrosomes are involved in controlling the movement of different cytoskeletal structures, including microtubules. They have an additional role in modifying the different membranes of animal cells, including cell membranes through phagocytosis.
Two perpendicular centrioles form a centrosome in an animal cell. One of them is a mother centriole, and the other one is a daughter centriole. Both the mother and daughter centriole are arranged in an orthogonal configuration. There are different protein complexes within the centrosome and a matrix surrounding it. The matrix is known as pericentriolar material. During cell division, the centrosome from the parent cell is segregated to the daughter cell. These centrosomes take part in the formation of the mitotic spindle.
Centrosomes also play a role in the organization of aster rays in the interphase stage pf the cell cycle. Aster rays have a notable effect on the polarity and adhesion of the cells.
Besides, centrosomes can direct the cellular protein traffic and nucleate the microtubules. However, this nucleation process depends on the movement of the associated protein and the polarity.
The function of the centrosome can be controlled in different phases of the cell cycle according to motility, adhesion, signaling, and polarity. It also coordinates the protein trafficking and organizing of the microtubules. In this way, centrosomes in animal cells play a vital role in the cell cycle.
How many centrosomes are in a cell?
Animal cells contain two centrosomes. These two centrosomes move to two opposite poles during cell division. Later, a spindle is formed between the two centrosomes that assist in transferring the replicated chromosomes to the respective daughter cells.
So, two centrosomes in an animal cell take an active part in duplicating and assisting in mitosis cell division.
When do centrosomes replicate?
Replication of centrosomes takes place during the S phase of the cell cycle. Centrosomes replicate once in each cell cycle. The result is the separation of two centrosomes in each daughter cell which move to two separate poles to form mitotic spindle. The division of centrosomes in a cell cycle is exactly similar to the division of DNA. Centrosomes also anchor the microtubules and shape the microtubule cytoskeleton system.
Bringing the discussion to the end, it can be said that although centrosomes are necessary organelles for cell division, plants lack this organelle. Even though centrosomes are absent in plants, cell division can still occur smoothly in plants. With the help of complex proteins and an organized microtubule system, cell division can still take place in plants without a centrosome.