4] Describe the phases involved in mitosis According to NCERT Class 11 Biology chapter 10 notes.
The M Phase is the period during which a cell divides or undergoes mitosis. This is the cell cycle's most dramatic stage. The letter 'M' stands for mitosis or meiosis, respectively. Karyokinesis and cytokinesis are both involved in M-phase.
Prophase: Prophase, the first stage of mitosis karyokinesis, occurs after the S and G2 phases of interphase. The new DNA molecules generated in the S and G2 stages are not separate, but rather interconnected. The onset of chromosomal material condensation characterizes prophase. Each chromosome, which can be seen with its sister-chromatids connected by centromere, becomes visible under a light microscope due to condensation. The nucleolus begins to go away. The nuclear membrane gradually disintegrates and vanishes. The centrosome, which had been duplicated during interphase, begins to migrate towards the cell's opposite poles.
Metaphase: The second phase of mitosis begins when the nuclear envelope completely disintegrates and the chromosomes are distributed throughout the cell's cytoplasm. Chromosome condensation is complete at this point and they may be seen clearly under the microscope. The chromosomes have been condensed to the point where they appear to be extremely short. Sister chromatids and centromeres take the stage. In the equatorial plane of the cell, all chromosomes are found. Metaphase plate is the term for this. The mitotic spindle has completed its development. Each chromosome's centromere is divided into two halves, each of which is associated with a chromatid.
Anaphase: Each chromosome's chromatids separate to generate two chromosomes known as daughter chromosomes. The spindle apparatus pulls the produced chromosomes away in the opposite direction. During mid-anaphase, chromosomes being dragged out resemble a cluster of bananas. Anaphase ends when each set of chromosomes reaches opposing poles of the cells.
Telophase: The telophase is karyokinesis' last stage. The centromeres with their chromosomes at the poles of the begin to uncoil, lengthen, and lose their uniqueness. The nucleolus starts to emerge again. Around the chromosomes, the nuclear membrane begins to emerge. Spindle threads disintegrate and are absorbed by the cytoplasm. In this way, a cell produces two daughter nuclei.
