What is the role of spindle fibers during mitosis?

Spindle fibres play a crucial role in mitosis by separating the chromosomes into the two daughter cells.

Spindle fibres, also known as spindle microtubules, are key components of the cell's cytoskeleton that play a pivotal role during mitosis, the process of cell division. They are responsible for the proper segregation of chromosomes, ensuring that each daughter cell receives an equal and identical set of chromosomes.

During the early stages of mitosis, specifically prophase, the cell's chromosomes condense and become visible. At the same time, the spindle fibres begin to form from a region called the centrosome, which duplicates and moves to opposite ends of the cell. These spindle fibres extend towards the centre of the cell, creating a structure known as the mitotic spindle.

As the cell enters metaphase, the chromosomes align at the cell's equator, also known as the metaphase plate. Each chromosome is attached to spindle fibres from both centrosomes by a structure called the kinetochore, located at the centromere of the chromosome. This attachment ensures that the forces exerted by the spindle fibres are balanced, keeping the chromosomes in the middle of the cell.

During anaphase, the sister chromatids (the identical copies of a chromosome) separate, and the spindle fibres begin to shorten. This shortening pulls the sister chromatids towards the opposite ends of the cell. This movement ensures that each daughter cell will receive one copy of each chromosome.

Finally, during telophase, the spindle fibres disassemble, and the chromosomes begin to decondense. The nuclear envelope re-forms around the chromosomes at each end of the cell, marking the end of mitosis. The cell then enters cytokinesis, where the cytoplasm divides, resulting in two identical daughter cells.

In summary, spindle fibres are essential for the accurate segregation of chromosomes during mitosis. They ensure that each daughter cell receives an identical set of chromosomes, maintaining genetic continuity from one generation to the next. Without spindle fibres, proper cell division would not be possible, leading to genetic abnormalities and potentially disease.