What is the region where sister chromatids are held together before they separate during cell division?

• A. Telomeres
• B. Nucleolus
• C. Mitochondria
• D. Centromeres

Answer: (D)

The region where sister chromatids stay attached before they separate is the centromere. This constricted part of each chromosome holds the two identical sister chromatids together through cohesion proteins until the chromosomes are ready to be pulled apart during mitosis. Microtubules attach to kinetochores located at the centromere, guiding the chromatids to align and then separate in anaphase when the cohesin proteins are cleaved. Telomeres protect chromosome ends and don’t hold chromatids together, nucleolus is the site of ribosomal RNA synthesis, and mitochondria are responsible for energy production. So, centromeres are the holding region that enables proper chromosome segregation.