Final answer:
Prophase marks the beginning of mitosis with the nuclear envelope dissolving and chromosomes coiling. Telophase is the end phase where chromosomes decondense and new nuclear envelopes form around them, signifying the imminent conclusion of cell division.
Step-by-step explanation:
Phases of Mitosis: Prophase and Telophase
During Prophase, the first phase of mitosis, the nuclear envelope begins to disintegrate into small vesicles, and the chromatin tightly coils to form visible chromosomes. This structural change allows the chromosomes to be easily managed and moved during cell division. As the nuclear envelope disappears, the nucleolus disperses, and the centrosomes move to opposite poles, pulling microtubules along to form the mitotic spindle.
In contrast, during Telophase, the final phase of mitosis, the chromosomes that have been pulled to opposite poles begin to uncoil and form chromatin, which signifies the genetic material is transitioning back to its working form inside newly formed nuclei. A new nuclear envelope is created around each set of chromosomes, and the nucleolus reappears within the nuclear area. At the conclusion of telophase, the cell has essentially two separate nuclei, setting the stage for the final separation into daughter cells during cytokinesis.