Answer:
In cell biology, the term "spindle" refers to a dynamic structure that is essential to mitosis, the process of cell division. It is in charge of ensuring that chromosomes accurately divide into two daughter cells during cell division.
The formation of the spindle is an intricate and tightly controlled process involving numerous cellular elements. It is made up of tubulin-containing microtubules, which are long, hollow cylindrical structures. Cell shape maintenance, intracellular transport, and cell division depend on microtubules.
Step-by-step explanation:
Prophase, the initial phase of mitosis, is when the spindle first forms. The duplicated chromosomes condense and become discernible under a microscope during this stage. Two centrosomes migrate to the cell's opposing poles simultaneously.
The nuclear envelope then disintegrates during prometaphase, allowing microtubules to connect with the chromosomes. The microtubules form the spindle apparatus, a bipolar array that extends from each centrosome towards the cell's nucleus.
Kinetochore microtubules and astral microtubules are two additional types of microtubules involved in the development of the spindle in addition to polar microtubules. Each chromosome's centromere region contains specialised protein structures called kinetochores, to which kinetochore microtubules bind.
During mitosis, these microtubules are essential for separating and aligning the chromosomes. The spindle is positioned within the cell by astral microtubules, which stretch from each centrosome to the cell's edge.
The chromosomes align along the cell's equatorial plane as mitosis develops into metaphase, generating a structure known as the metaphase plate. The kinetochore microtubules from each centrosome bind to the kinetochores of sister chromatids, ensuring that each chromosome is appropriately aligned and anchored to both spindle poles.
Sister chromatids split apart and are drawn in different directions to the spindle poles during anaphase. The kinetochore microtubules shortening that causes the chromosomes to be physically forced apart promotes this migration. Polar microtubules lengthen and press against one another at the same time, lengthening.