AP BIOLOGY

Detailed explanation-1: -The spindle fibers form during prophase. During metaphase of cell division, the spindle fibers radiate from the centrioles at the opposite poles. Some of them attach to the kinetochores of the chromosomes while others bind to the arms of the chromosomes, still others continue to grow.

Detailed explanation-2: -Prophase: the nuclear envelope breaks down, chromosomes condense, and spindle fibers connect to sister chromatids. Metaphase: spindle fibers pull sister chromatids to the metaphase plate at the equator of the cell. Anaphase: spindle fibers separate sister chromatids to opposite poles of the cell.

Detailed explanation-3: -The sister chromatids are pairs of identical copies of DNA joined at a point called the centromere. Then, a structure called the mitotic spindle begins to form. The mitotic spindle is made of long proteins called microtubules that begin forming at opposite ends of the cell.

Detailed explanation-4: -Prophase: Spindle fibers form at opposite poles of the cell. In animal cells, a mitotic spindle appears as asters that surround each centriole pair. The cell becomes elongated as spindle fibers stretch from each pole. Sister chromatids attach to spindle fibers at their kinetochores.