Question

how does a centrosome work in a plant cell without centrioles?

Answer 1

http://www.cellsalive.com/cells/centriol.htm

ANIMAL CELL CENTROSOME: mitosisThe centrosome, also called the "microtubule organizing center", is an area in the cell where microtubles are produced. Within an animal cell centrosome there is a pair of small organelles, the centrioles, each made up of a ring of nine groups of microtubules. There are three fused microtubules in each group. The two centrioles are arranged such that one is perpendicular to the other.

During animal cell division, the centrosome divides and the centrioles replicate (make new copies). The result is two centrosomes, each with its own pair of centrioles. The two centrosomes move to opposite ends of the nucleus, and from each centrosome, microtubules grow into a "spindle" which is responsible for separating replicated chromosomes into the two daughter cells.

PLANT CELL CENTROSOME: Plant cells have centrosomes that function much like animal cell centrosomes. However, unlike centrosomes in animal cells, they do not have centrioles.

Answer 2

i asked the question after i read it.

Answer 3

Microtubules in plant cells

Plant cells do not have a centrosome and hence no single observable nucleation site from which new microtubules are produced.

In plant cells there are many small nucleation sites and these and the microtubules they initiate are located in the cell on the cytoplasm side of the plasma membrane and just below it. They are aligned parallel to one another but are closely interlinked to form a network layer running parallel to the plasma membrane throughout the cell.

Intriguingly plant cell microtubules can re-align themselves in response to chemical stimulation. Microtubules in cells near the root tip are found at right angles to the direction of the growth of the root. Further back from the root tip the microtubules rotate through a right angle and align themselves to become parallel to the direction of root growth.
The importance of microtubules in plant cells should not be underestimated. Depolymerisation of microtubules causes cellulose to be laid down in a disorganised way. The root tip becomes a mass of such cells and although they expand they cannot elongate and the tissue grows in a distorted manner. Chemicals such as colchicine inhibit polymerisation and hence stop the production of microtubules. Some synthetic weedkillers bring about microtubule depolymerisation.

http://www.bscb.org/?url=softcell/cytoskeleton

Answer 4

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2106853/pdf/239.pdf

Micrograph depicting oblique section through lateral wall (cw) separating two cells of a
Juniperus root tip. The microfibrillar structure of the cell wall, evident in this preparation, is organized
with fibrils parallel to the tubules in the cell cortex. Here again, the tubules next to the cell surface are
parallel, whereas those deeper in the cytoplasm are less well ordered. × 100,000.