Final answer:
During anaphase of mitosis, spindle fibers separate sister chromatids by shortening like a fishing line, ensuring each cell pole receives a complete set of chromosomes. These fibers are crucial for the accurate distribution of genetic material, and their role begins during prophase and ends following telophase with cytokinesis completing the process.
Step-by-step explanation:
The phases of mitosis consist of prophase, metaphase, anaphase, and telophase, along with cytokinesis. During anaphase, sister chromatids are separated at the centromeres and pulled apart by the spindle fibers. These spindle fibers, composed of microtubules, are crucial as they shorten, functioning much like reeling in a fishing line, to move the chromatids to opposite poles of the cell. After anaphase ends, each pole has a complete set of chromosomes, hence ensuring that each daughter cell will have a full set of genetic material.
During cytokinesis in animal cells, the cytoplasm divides to form two separate daughter cells, each encapsulating one of the two pole sets of chromosomes. The role of spindle fibers, which emanate from the centrosomes, during the whole process is to ensure the proper segregation of genetic material.
If a cell were to skip metaphase during mitosis, the chromosomes would not properly align at the cell equator, potentially leading to incorrect chromosome number in the daughter cells, a condition known as aneuploidy.