AP BIOLOGY

Detailed explanation-1: -The two “sister” chromatids are joined at a constricted region of the chromosome called the centromere. During cell division, spindle fibers attach to the centromere and pull each of the sister chromatids to opposite sides of the cell. Soon after, the cell divides in two, resulting in daughter cells with identical DNA.

Detailed explanation-2: -After DNA is replicated each chromosome consists of paired sister chromatids held together by cohesin.

Detailed explanation-3: -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-4: -Centromere is a primary constriction present on the chromosome where the chromatids are held together.

Detailed explanation-5: -The two chromatids of a duplicated chromosome are held together at a region of DNA called the centromere (see figure below). Centromeres are the attachment points for microtubules, which are responsible for the guiding the movement of chromosomes during mitosis and meiosis.