define phases of mitosis
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Mitosis is completed through 2 main steps. Those two steps are Karyokinesis (nuclear membrane) and cytokinesis (cytoplasmic membrane).
Now, Karyokinesis is completed through 4 steps.
Let's see them step by step.
A. Prophase : In this phase, condensation of basically thin thread like chromosomes starts. Due to this, they become short and thick and they start to appear along with their pairs of sister chromatids. Centrioles duplicate and each centriole moves to opposite poles of the cells. Nuclear membrane and nucleolus start to disappear.
B. Metaphase : Nuclear membrane completely disappears in metaphase. Chromosomes complete their condensation and become clearly visible along with their sister chromatids. All chromosomes are arranged parallel to the equatorial plane ( central plane of the cell ). Special type of flexible protein fibres ( spindle fibres ) are formed between centromere of each chromosome and both centrioles.
C. Anaphase : In this phase, centromeres split and thereby sister chromatids are pulled apart in opposite directions with the help of spindle fibres. Separated sister chromatids are called as Daughter chromosomes. In this way, each set of chromosomes reach at two opposite poles of the cell.
D. 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 and 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 fibres completely disappear.
In this way, Karyokinesis is completed.
Cytoplasm divides by cyrokinesis and two new cells 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 plants, a cell plate is formed exactly along the midline of the cell and thus, the cytokinesis is completed.
Now, Karyokinesis is completed through 4 steps.
Let's see them step by step.
A. Prophase : In this phase, condensation of basically thin thread like chromosomes starts. Due to this, they become short and thick and they start to appear along with their pairs of sister chromatids. Centrioles duplicate and each centriole moves to opposite poles of the cells. Nuclear membrane and nucleolus start to disappear.
B. Metaphase : Nuclear membrane completely disappears in metaphase. Chromosomes complete their condensation and become clearly visible along with their sister chromatids. All chromosomes are arranged parallel to the equatorial plane ( central plane of the cell ). Special type of flexible protein fibres ( spindle fibres ) are formed between centromere of each chromosome and both centrioles.
C. Anaphase : In this phase, centromeres split and thereby sister chromatids are pulled apart in opposite directions with the help of spindle fibres. Separated sister chromatids are called as Daughter chromosomes. In this way, each set of chromosomes reach at two opposite poles of the cell.
D. 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 and 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 fibres completely disappear.
In this way, Karyokinesis is completed.
Cytoplasm divides by cyrokinesis and two new cells 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 plants, a cell plate is formed exactly along the midline of the cell and thus, the cytokinesis is completed.
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Information on Mitosis :-
=>This kind of cell division takes place in the somatic cells.
=>Only two daughter cells are formed in this division.
=>This is necessary for the growth and repair of the cells.
=>Diploid daughter cells are remained.
=>Crossing over doesn't take place here.
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