Question 57

DNA is condensed and then sister chromatids are organized along the midline of the cell.

During the transition from prophase to metaphase in mitosis, DNA condenses to form visible chromosomes, and the sister chromatids align along the cell's equatorial plane, preparing for separation.

A) Chromatids are separated and isolated into separate daughter nuclei.

This option describes an event that occurs later in mitosis, specifically during anaphase, when the sister chromatids are pulled apart towards opposite poles of the cell. Therefore, it is incorrect in the context of the transition from prophase to metaphase.

B) Chromosomes are uncondensed and arranged randomly throughout the cell.

This statement is inaccurate as, by the end of prophase and into metaphase, chromosomes are fully condensed and organized. They are not random; instead, they are positioned in a specific arrangement along the metaphase plate.

C) Chromosomes are aligned along the center of the cell and then pulled apart into separate chromatids.

Although this option describes a part of the mitotic process, it inaccurately conflates two stages. The alignment of chromosomes occurs in metaphase, but the pulling apart of chromatids happens in the subsequent anaphase stage.

D) DNA is condensed and then sister chromatids are organized along the midline of the cell.

This option accurately describes the events taking place during the transition from prophase to metaphase. The DNA condenses into distinct chromosomes, and sister chromatids align at the cell's equator, which is a key characteristic of metaphase.

Conclusion

The correct answer, option D, clearly encapsulates the critical events occurring during the transition from prophase to metaphase, highlighting the condensation of DNA and the organization of sister chromatids at the cell's midline. Other options misrepresent this phase of mitosis, either by describing events that happen in different stages or by providing incorrect details about chromosomal organization.