Final answer:
Sister chromatid cohesion, maintained by cohesin proteins, is crucial for the alignment and proper segregation of chromosomes until anaphase II of cell division.
Step-by-step explanation:
Sister chromatid cohesion is maintained by cohesin proteins until anaphase II. During DNA duplication in the S phase of interphase, cohesin ensures that each chromosome's identical copies (sister chromatids) are bound together, mostly at the centromere.
The process continues during mitosis where the sister chromatids line up at the metaphase plate and the kinetochore becomes attached to the mitotic spindle.
Cohesion is necessary for the alignment and proper segregation of chromosomes. It's only during anaphase that cohesin proteins break down allowing the sister chromatids to separate and move to opposite poles of the cell.