Sister chromatids are two identical copies of a single chromosome that are formed during DNA replication in the S phase of the cell cycle. They are joined together by a specialized region of the chromosome called the centromere. Sister chromatids remain attached until they are separated during cell division (mitosis or meiosis) to ensure accurate distribution of genetic material to daughter cells.

Key Points:

• Sister chromatids are genetically identical copies of one chromosome.
• They are formed during the DNA replication process in the S phase of interphase.
• They are connected by the centromere and held together by cohesin proteins.
• Separation of sister chromatids occurs during anaphase of mitosis or anaphase II of meiosis.

This formation allows for proper chromosome stability, alignment, and segregation in cell division.