Cell division is the driving process of reproduction at the cellular level. Most eukaryotic cells divide in a manner where the ploidy or the number of chromosomes remains conserved, except in the case of germ cells where the number of chromosomes is halved. Let’s see different phases of Mitosis.
Mitosis is the phase of the cell cycle where the nucleus of a cell is divided into two nuclei with an equal amount of genetic material in both the daughter nuclei. It succeeds the G2 phase and is succeeded by cytoplasmic division after the separation of the nucleus. The processes occurring during mitosis are trying to separate from each other but for the convenience of understanding, it has been divided into the following stages which are explained below.
Stages of Mitosis
The different phases of Mitosis occurring during cell division are given as follows-
Prophase immediately follows S and G2 phase of the cycle and is marked by condensation of the genetic material to form compact mitotic chromosomes composed of two chromatids attached at the centromere. The completion of prophase is characterized by the initiation of the assembly of the mitotic spindle, the microtubules, and the proteinaceous components of cytoplasm that help in the process. The nuclear envelope starts disintegrating.
The nuclear envelope completely disintegrates at the onset of metaphase and the condensed chromosomes spread throughout the cytoplasm. These chromosomes are composed of two sister chromatids held at the center by centromeres. The spindle fibers attach to a disc-like structure at the surface of centromeres, known as kinetochores. The spindle fibers from one centriole attach to only one sister chromatid. The chromosomes aligned along the equator of the cytoplasm, an arrangement characteristic of metaphase known as metaphase plate.
The onset of anaphase is marked by the splitting of the sister chromatids. These sister chromatids become the chromosome of the daughter nuclei. The chromosomes are then pulled towards the pole by the fibers attached to the kinetochores of each chromosome. The centromere of each chromosome leads at the edge while the arms trail behind it.
The chromosomes that cluster at the two poles start coalescing into an undifferentiated mass, as the nuclear envelope starts forming around it. The nucleolus, Golgi bodies and ER complex, which had disappeared at the completion of prophase start to reappear.
Telophase is followed by cytokinesis, which denotes the division of cytoplasm to form two daughter cells. Thus it marks the completion of cell division.
To learn in more detail about mitosis cell division, visit Byju’s.
Practise This Question