What Is the Mitosis Phase of the Cell Cycle?

In this what is the mitosis phase of the cell cycle? post we have briefly explained about mitosis phase of cell cycle, prophase, metaphase, anaphase, telophase, and cytokinesis.

Mitosis Phase of Cell Cycle

The process by which the nucleus of a cell splits is known as mitosis. In mitosis, two sister chromatids that comprise each chromosome separate from each other and shift towards opposite poles of the cell. Mitosis phase of cell cycle can occur through four stages. These phases are known as metaphase, prophase and telophase. They are illustrated in Figure:1 and are described in more detail below.

Mitotic Phase of Cell Cycle - Mitosis and Cytokinesis

Mitosis is a phase of the eukaryotic cell cycle. It takes place between DNA replication and the creation of two cells. Mitosis phase of cell cycle is divided into four stages: metaphase, prophase and telophase.

Prophase

Mitotic Phase of Cell Cycle - Mitosis and Cytokinesis

Mitosis Phase of Cell Cycle: The stage of prophase that occurs later is known as Prometaphase. The spindle forms during the mitosis prophase. The spindles begin to connect with the Kinetochores of the centromeres of sister chromatids at the time of Prometaphase.

The most lengthy and first stage of mitosis phase of cell cycle is called prophase. In prophase, chromatin is dissolved into chromosomes, and then the nucleus’s envelope (the membrane that surrounds the nucleus) is broken down. In animals, close to the nucleus breaks up and then move to opposite poles within the cells. 

Centrioles are tiny organelles that can be that is found in only cells of the eukaryotic family that ensure the cells that are created after division have a complete collection of chromosomes. When the centrioles break apart, a spindle begins to develop between them. As illustrated in Figure: 2, the blue spindle is composed of microtubules containing fibres.

Metaphase

Mitotic Phase of Cell Cycle - Mitosis and Cytokinesis

Mitosis Phase of Cell Cycle: Chromosomes, composed of sister chromatids, form a line in the middle or equator of the cell in metaphase. The blue lines represent spindles, and the orange rectangles located at the cell’s poles are centrioles. The spindles from opposite centrioles connect, and others attach to the kinetochores on the sister chromosomes on their respective side. Each chromosome is connected to two spindles.

In metaphase, spindle fibres connect to the centromeres of every twin chromatid pair. As shown in Figure:3, the sister chromatids are aligned at the equator or the centre within the cell. The spindle fibres ensure that sister chromatids are separated and move to different daughter cells once the cell splits. 

Certain spindles don’t attach to the centromeres of the chromosomes. Instead, they connect and get larger. The elongation that spindles do not have is not connected to centromeres. They extend the entire cell. This can be seen in the following figure:

Anaphase

Mitosis Phase of Cell Cycle: Anaphase is when sister’s chromatids split into pieces and shift towards the opposite pole by using spindles. The newly separated sister chromatids can be known as chromosomes.

Anaphase is when sister chromatids separate and centromeres are split. The sister chromatids break apart due to the contraction of spindle fibers. It’s a bit like reeling in a fish through making the fishing line shorter. One sister chromatid is moved to one side of the cell. Meanwhile, one sister is moved toward the opposing direction. After anaphase the poles of the cell contains the complete set of chromosomes.

Telophase

Mitosis Phase of Cell Cycle: Telophase the chromosomes decondense; spindles start to disappear, two nuclei form in a cell.

The chromosomes are positioned at the opposite pole. They begin decondensed (unravel) before relaxing again into a stretched out chromatin structure. Mitotic spindles depolymerize into tubulin monomers, which can construct cells with cytoskeletal elements for every daughter cell. Nuclear envelopes are formed around nucleosomes, while chromosomes are formed in the nuclear region.

Cytokinesis

Cytokinesis is the last phase of cell division in eukaryotes and prokaryotes. In cytokinesis, the cytoplasm splits, and cells divide. This process differs in animals and plants, as illustrated in Figure:6. In animal cells, that cell’s plasma membrane presses towards the equator of the cell till two daughters cells develop. An in-plant cell, the cell plate is formed on the equator of the parent cell. After that, a new plasma wall and membrane form around the plate.

Mitosis Phase of Cell Cycle: Cytokinesis represents the final phase of eukaryotic cell division. It happens differently in the animal (left) or the plant (right) cell. An elongated microfilament-like ring is in the middle of the elongated animal cell. It creates a depression, which is known as the cleavage furrow. The invagination eventually separates the cell’s cytoplasm into two cells. A cell plate is formed within the central part of the plant cell that has been elongated. Then, a newly formed plasma membrane and a cell wall develop on each side of the cells plate. Image Source: https://bio.libretexts.org/

Take Away

Mitosis phase of cell cycle can occur through four stages. These phases are known as metaphase, prophase and telophase. Cytokinesis is the last phase of cell division in eukaryotes and prokaryotes. In cytokinesis, the cytoplasm splits, and cells divide. 

Further Readings