Final answer:
The first centromeres studied at the molecular level were isolated from yeast, and kinetochores form at the centromere to attach chromosomes to microtubules during cell division. Sister chromatids are separated during Anaphase II of meiosis.
Step-by-step explanation:
The first centromeres studied at the molecular level were isolated from yeast. Yeast centromeres were crucial for understanding the basic mechanisms of chromosome segregation during cell division. A centromere is a region on a chromosome that joins sister chromatids together, and it is where the kinetochore forms, which is essential for the attachment of the chromosome to microtubules during cell division. During meiosis, sister chromatids are separated from each other in Anaphase II, which is the stage after metaphase II where the centromeres are split and the chromatids are pulled apart by the spindle fibers to opposite poles of the cell. The study of centromeres contributed significantly to our understanding of cell cycle control and the molecular mechanisms that underpin genetic inheritance.
The first isolation of a cytoplasmic factor from Xenopus eggs that controlled the cell cycle also underlined the importance of understanding cell division processes such as meiosis and mitosis, and how they are regulated at a molecular level. Research on centromeres, including identifying the composition and function of the kinetochore, has been foundational for genetic and cell biology.