Centrosomes are absent in plant cells because plant cells have a unique cell structure and division process. Unlike animal cells, which have centrosomes made up of two centrioles, plant cells lack centrosomes and centrioles. Instead, plant cells have specialized microtubule-organizing centers called spindle poles that perform similar functions to centrosomes during cell division.
During cell division in animal cells, the centrosomes help organize the spindle fibers, which pull the chromosomes apart into two separate nuclei. However, in plant cells, the spindle fibers form from the spindle poles, which are located at opposite ends of the cell. The spindle fibers then attach to the chromosomes and pull them apart into two nuclei.
Furthermore, plant cells have rigid cell walls made up of cellulose that provide structural support and help resist the forces generated during cell division. This means that plant cells do not require centrosomes to provide the same level of support and organization during cell division as animal cells do.