Final answer:
Spindle fibers shorten to pull sister chromatids apart during anaphase, resembling the reeling in of a fishing line.
Step-by-step explanation:
During anaphase, spindle fibers shorten to pull sister chromatids towards opposite poles of the cell, while non-kinetochore microtubules lengthen the cell. The process is akin to reeling in a fish, with the kinetochore microtubules decreasing in length to move the chromosomes. Conversely, the polar microtubules extend, pushing the cell poles apart, which helps in cell elongation. In this phase, each new cell prepares to inherit a complete set of chromosomes.
During anaphase, the spindle fibers shorten to push and pull the chromosomes. The spindle fibers are composed of microtubules, and the kinetochore microtubules, which are attached to the chromosomes, are responsible for pulling the sister chromatids apart by shortening. On the other hand, the non-kinetochore microtubules, known as polar microtubules, lengthen to help separate the poles of the cell.