Final answer:
Kinetochores attach chromatids to spindle microtubules. They are essential for the accurate segregation of chromosomes during cell division, particularly in the stages of prometaphase and metaphase.
Step-by-step explanation:
Kinetochores play a crucial role during cell division, especially in the processes of mitosis and meiosis. During the later stages of prophase, also known as prometaphase, the nuclear membrane breaks down, allowing spindle microtubules to access the chromosomes. Each chromosome's centromere has a specialized structure made of proteins called the kinetochore, which facilitates the attachment of the chromosome to the spindle microtubules.
As metaphase commences, the sister chromatids are lined up at the cell's equator, attached to spindle fibers emanating from opposite poles of the cell. The kinetochores ensure that each sister chromatid will separate correctly and migrate to the resulting daughter cells when the cell divides, ensuring genetic material is equally partitioned. To directly answer the question, kinetochores attach chromatids to spindle microtubules, ensuring accurate chromosome segregation during cell division.