Final answer:
The statement about DNA replication during the S phase leading to the formation of sister chromatids attached at the centromere is true, though it is cohesin proteins which hold them together.
Step-by-step explanation:
The statement is mostly true. During the S phase of the cell cycle, DNA is replicated, and each chromosome forms two identical copies known as sister chromatids. These chromatids are indeed attached to each other at a region called the centromere. The chromatids are tightly associated with proteins called histones, around which DNA is wrapped to form the structure of chromatin. However, it is important to note that they are held together at the centromere by cohesin proteins rather than the centromere itself. This structure is maintained until the chromatids are separated during later stages of cell division, specifically, during anaphase of mitosis.