Mitosis

Mitosis is the division of the nucleus that produces two daughter nuclei, each genetically identical to the parent nucleus and to each other, with the same number of chromosomes. In a diploid cell, both daughter cells are diploid.Mitosis follows interphase, when the DNA has already been replicated so that each chromosome has two sister chromatids. During mitosis the sister chromatids are separated, and one chromatid of every chromosome goes to each new nucleus.Mitosis is a continuous process, but it is described in four stages:prophase → metaphase → anaphase → telophaseIt is followed by cytokinesis, when the cytoplasm divides to form two cells. Each stage is covered in its own lesson.Mitosis is important for:
• growth of multicellular organisms, by increasing the number of cells
• repair and replacement of damaged or worn-out cells, e.g. skin and the lining of the gut
• asexual reproduction, e.g. in yeast, and in plants that grow from runners or tubersBecause the new cells are genetically identical, mitosis keeps the genetic information the same in every body cell. Mitosis does not produce genetic variation.In plants, mitosis happens mainly in meristems, such as the root tip. Mitosis can be seen in a root tip squash: the tip is softened in warm hydrochloric acid to separate the cells, stained with a DNA stain such as toluidine blue or acetic orcein, and gently squashed under a coverslip to form a single layer of cells, which are then viewed with a light microscope.