AP BIOLOGY

Detailed explanation-1: -The two “sister” chromatids are joined at a constricted region of the chromosome called the centromere.

Detailed explanation-2: -A sister chromatid refers to the identical copies (chromatids) formed by the DNA replication of a chromosome, with both copies joined together by a common centromere. In other words, a sister chromatid may also be said to be ‘one-half’ of the duplicated chromosome. A pair of sister chromatids is called a dyad.

Detailed explanation-3: -While centromeres are typically located in the central area of a chromosome, they can also be located near the mid-region or at a number of different positions on the chromosome. Specialized zones on centromeres called kinetochores attach the chromosomes to spindle fibers in prophase in mitosis.

Detailed explanation-4: -Centromere is a primary constriction present on the chromosome where the chromatids are held together.

Detailed explanation-5: -Sister chromatids are physically held together by cohesin, which is a protein complex consisting of four core subunits (Fig.