Where are two sister chromatids held together?

Where are two sister chromatids held together?

• A. Centromere
• B. Chromatin
• C. Telomere
• D. Kinetochore

Answer: (A)

Sister chromatids are held together at the centromere, the constricted region of a chromosome where cohesin proteins keep the two copies tightly linked as the cell prepares to divide. This centromeric region is also where the kinetochore—the protein complex that attaches spindle fibers during mitosis—forms, guiding the chromatids to be pulled apart when the time comes. Chromatin refers to the entire DNA-protein material of the chromosome, not the specific point where the copies stay joined. Telomeres are the protective ends of chromosomes, not the joining site. The kinetochore, although it sits at the centromere and is essential for pulling chromatids apart, is the attachment point for spindle fibers rather than the glue that holds the chromatids together.

Sister chromatids are held together at the centromere, the constricted region of a chromosome where cohesin proteins keep the two copies tightly linked as the cell prepares to divide. This centromeric region is also where the kinetochore—the protein complex that attaches spindle fibers during mitosis—forms, guiding the chromatids to be pulled apart when the time comes. Chromatin refers to the entire DNA-protein material of the chromosome, not the specific point where the copies stay joined. Telomeres are the protective ends of chromosomes, not the joining site. The kinetochore, although it sits at the centromere and is essential for pulling chromatids apart, is the attachment point for spindle fibers rather than the glue that holds the chromatids together.