Mitosis is a vital process of somatic cell division, ensuring equal distribution of replicated chromosomes into two daughter cells. It comprises several phases, but the last two—Anaphase and Telophase—play key roles in chromosome segregation and reformation of nuclei, preparing the cell for cytokinesis and the formation of genetically identical daughter cells.
Anaphase is characterized by the separation of sister chromatids, which are identical copies of each chromosome created during the S phase of interphase. Each sister chromatid is attached to spindle fibers originating from opposite centrosomes (poles of the cell).
The process begins when the enzyme separase cleaves the cohesin proteins holding sister chromatids together at the centromere. After they separate, the sister chromatids, which become individual chromosomes, are drawn to opposite ends of the cell as the spindle microtubules contract. This movement is aided by motor proteins such as dynein and kinesin, which "walk" along the microtubules.
During anaphase, the cell elongates due to polar microtubules pushing apart, which helps in physically separating the two sets of chromosomes. The precise segregation of chromosomes at this stage is critical; any errors can result in aneuploidy, a condition linked to genetic disorders and cancers.
Telophase marks the reversal of many changes that occurred during early mitosis. Once the chromosomes arrive at the poles, they begin to de-condense, unwinding from tightly packed chromatids back into the less condensed chromatin form, making the DNA accessible for transcription and other cellular processes.
During this phase, the nuclear membrane reforms around each set of chromosomes, resulting in the formation of two separate nuclei inside the cell. The nucleolus, which had disappeared during prophase, reappears inside each nucleus. The mitotic spindle breaks down as the microtubules depolymerize.
Telophase effectively completes the process of nuclear division (karyokinesis), setting the stage for cytokinesis, where the cytoplasm divides, creating two independent daughter cells. Each daughter cell inherits an identical set of chromosomes, ensuring genetic consistency across somatic cells.
Summary: Anaphase ensures accurate and equal separation of sister chromatids, preventing genetic imbalance, while telophase restores the nuclear environment and prepares the cell for physical division. Together, these phases complete mitosis, enabling healthy growth and tissue repair in multicellular organisms.
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