Final answer:
The kinetochore ensures that half of the chromosome moves from one side to the other during cell division by attaching sister chromatids to the mitotic spindle. Cohesin proteins bind the chromosomes together until they separate. Genetic recombination occurs through crossing over during meiosis.
Step-by-step explanation:
The correct answer to what ensures that half of the chromosome moves from one side to the other is B) Kinetochore. During cell division, specifically during the metaphase stage of mitosis, the kinetochore becomes attached to the mitotic spindle fibers. This connection to the spindle fibers is critical for the alignment of the sister chromatids at the metaphase plate, and their subsequent separation into two sets as the cohesin proteins break down during anaphase to ensure even distribution of chromosomes to the daughter cells.
In prophase I, during meiosis, the homologous chromosomes are paired up and linked together by cohesin proteins. These proteins maintain the structural integrity of the chromosomes until they are ready to be pulled apart. Furthermore, genetic recombination, which increases genetic diversity, occurs by the process of crossing over during prophase I of meiosis when homologous chromosomes exchange portions of their DNA.