Final answer:
During mitosis, chromatin condenses into visible chromosomes, facilitating chromosome segregation. The spindle apparatus attaches to these chromosomes, allowing them to line up and be evenly distributed into two daughter cells. The first level of DNA organization is maintained by histones, and chromosome cohesion is facilitated by cohesin proteins.
Step-by-step explanation:
Early in mitosis, chromatin condenses which makes chromosome segregation take place more easily as a result. This condensation process is crucial because it turns the loose and stringy chromatin into tightly packed chromosomes, which are then able to be separated accurately into two new cells. During prophase, the first phase of mitosis, chromatin condenses into visible chromosomes and the spindle fibers form to attach to chromosomes, leading to their eventual segregation during anaphase. Following prophase, in metaphase, the chromosomes line up in the center of the cell which is critical for their even distribution into the daughter cells. The separation of sister chromatids occurs later in the process, ensuring that each new cell receives the correct number of chromosomes.
The nuclear envelope breaks down at the start of mitosis to allow the spindle fibers, made of microtubules, to attach to the chromosomes at the centromeres. The spindle fibers are essential for the movement and segregation of chromosomes. As for chromosomal structure, the first level of DNA organization in a eukaryotic cell is maintained by histone molecules. DNA replicates in the S phase of interphase, and the replicated chromosomes, which are now composed of two sister chromatids, are held together by cohesin proteins. These structures are all part of the essential organization that allows for chromosome segregation during mitosis.