MITOSIS V Tamilarasi K V Thakkolam MITOSIS n

MITOSIS V. Tamilarasi K. V. Thakkolam

MITOSIS n Mitosis is the process of forming identical daughter cells by replicating and dividing the original chromosomes, in effect making a cellular xerox.

PROPHASE Prophase is the first stage of mitosis proper. n Chromatin condenses (remember that chromatin/DNA replicate during Interphase), n The nuclear envelope dissolves, centrioles divide and migrate, kinetochores and kinetochore fibers form, and the spindle forms. n

METAPHASE 1) Centriole at the opposite pole 2) The chromosomes migrate to the equator of the spindle where the spindles attach to the kinetochore fibers. 3) Spindle apparatus well developed 4) N. Membrane and nucleolus dissappeared

ANAPHASE n It begins with the separation of the centromeres, and the pulling of chromatids (we call them chromosomes after the centromeres are separated) to opposite poles of the spindle.

TELOPHASE The chromosomes reach the poles of their respective spindles. n The nuclear envelope reforms, chromosomes uncoil into chromatin form, and the nucleolus (which had disappeared during Prophase) reform. n Two daughter nuclei are formed. n

CYTOKINESIS ANIMAL CELL PLANT CELL

Cytokinesis Animal Cell n Appearance of furrow in the plasma membrane, deepens and joins in the centre dividing the cell cytoplasm into two. Plant Cell n Cell wall formation starts in the centre by the formation of cell plate and grows outward to meet the existing lateral walls, thus cell divides into two.

IN ANIMAL CELL

Significance of mitosis n n n The growth of multicellular organisms is due to mitosis. Involves in cell repair. Mitotic divisions in the meristematic tissues in plants result in a continuous growth. It results in the formation of two cells. Daughter cells are similar to parent cell.

Questions n n n 1. Why is mitosis called equational division? 2. What is the metaphase plate? 3. What are the significance of mitosis? 4. In which phase centromere divides? 5. In which phase the N. Membrane disappears?