Final answer:
The centromere is the key DNA sequence where sister chromatids are held together and attached during chromosome segregation in cell division, including mitosis and meiosis.
Step-by-step explanation:
The centromere is the specialized DNA sequence that provides an attachment point for the segregation of duplicated chromosomes. During the S phase of interphase, DNA replication results in two identical copies of each chromosome, known as sister chromatids, which are held together at the centromere by cohesin proteins. This cohesin link maintains the connection between sister chromatids until they are separated during cell division at anaphase II.
In meiosis, particularly during prophase I, homologous chromosomes pair up and exchange genetic material through a process known as recombination or crossover. The synaptonemal complex and recombination nodules facilitate this exchange, eventually leading to the creation of chiasmata, which hold the homologous chromosomes together until anaphase I. In summary, the centromere is critical for proper chromosome segregation, ensuring that each new cell inherits the correct complement of chromosomes post-division.