Which organelle is involved in organizing spindle fibers during cell division?

• A. Ribosome
• B. Mitochondrion
• C. Centriole
• D. Golgi apparatus

Answer: (C)

During cell division, the spindle fibers are organized by a structure that sits at the cell’s poles and acts as the main microtubule organizing center. In animal cells, centrioles reside in the centrosome and duplicate before division, forming two poles from which microtubules grow to create the spindle apparatus. This spindle then attaches to chromosomes and helps pull sister chromatids apart, guiding proper segregation into daughter cells. The other organelles listed don’t organize spindle fibers: ribosomes make proteins, mitochondria provide energy, and the Golgi apparatus processes and ships proteins. Plants have spindle organization too, but often without centrioles, relying on other organizing centers; in many animal-cell contexts, centrioles are the classic directors of spindle formation.