Final answer:
Spindle fibers are involved in prophase, metaphase, anaphase, and telophase, assisting in the movement and segregation of chromosomes during cell division.
Step-by-step explanation:
Phases of Cell Division With Spindle Fibers
Spindle fibers are structures that play a crucial role in cell division, specifically during the process of mitosis and meiosis. They are involved in the movement and segregation of chromosomes to daughter cells. The phases where spindle fibers are present include:
- Prophase: Spindle fibers begin to form as the cell prepares for chromosome separation. The fibers extend from the centrioles, which have moved to opposite ends of the cell.
- Metaphase: The spindle fibers attach to each chromosome's centromere and align the chromosomes at the cell's equatorial plane, known as the metaphase plate.
- Anaphase: The spindle fibers shorten, which reels in the divided sister chromatids toward opposite poles, similar to pulling a fish in by shortening the fishing line.
- Telophase: Once chromosomes reach the poles, the spindle fibers disassemble, nuclear envelopes re-form around the chromosomes, and the cell completes division with the process of cytokinesis.
These actions ensure proper segregation of genetic material, which is vital for the generation of genetically stable daughter cells.