Explain mitosis cell division with diagram
Answers
SOMATIC CELLS AND STEM CELLS DIVIDE BY MITOSIS.MITOSIS IS COMPLETED THROUGH TWO MAIN STEPS. THOSE TWO STEPS ARE KARYOKINESIS AND CYTOKINESIS. KARYOKINESIS IS COMPLETED THROUGH FOUR STEPS.
PROPHASE : in prophase condensation of thin thread like chromosomes starts. due to this they become thick and short and they start to appear with their sister chromatids. centrioles duplicate and each centrioles moves to opposite poles of the cells. nuclear membrane and nucleolus start to disappear,
METAPHASE: nucear membrane completely disappear in metaphase. chromosomes complete their condensation and become clearly visible along with their sister chromatids. all chromosomes are arranged parallel to equatorial plane (central plane) of the cell. special type of flexible protein fibers are formed between centromere of each chromosomes and both centrioles.
ANAPHASE: in anaphase centromere split and thereby sister chromatids of each chromosomes separate and they are pelled apart in opposite directions with the help of spindle fibers. separated sisiter chromatids are called as daughter chromosomes. chromosomes being pulled appear like bunch of bananas. in this way each set of chromosomes reach at two opposite poles of the cell.
TELOPHASE: the chromosomes which have reached at opposite poles of the cell now start to decondense due to which they again become thread like thin ans invisible. nuclear membrane is formed around each set of chromosomes reached at poles. thus two daughter nuclei are formed in a cell. nucleolus also appears in each daughter nucleus. spindle fibers completely disappear.
in this way karyokinesis completes and cytokinesis begins.
the cytoplasm divides by cytokinesis and two new cewlls are formed which are called as daughter cells. in this process a notch is formed at the equatorial plane of the cell which deepens gradually and thereby two new cells are formed. however in case of plant cells instead of the notch a cell plate is formed exactly along midline of the cell and thus cytokinesis is completed.