Mitosis By: Timmy Mudlock Zane Stelevich

Prophase

Prophase in an Animal Cell

Prophase in a Plant Cell

Description During Prophase, changes occur in both the nucleus and the cytoplasm. In the nucleus, in the nucleoli disappear. The chromatin fibers become more tightly coiled and folded into discreet chromosomes observable with a light microscope Each duplicated chromosomes appears as two identical sister chromatids joined at the centromere. In the cytoplasm, the mitodic spindle forms; it is made of microtubules and associated proteins arranged between the two centrosomes. During prophase, the centrosomes move away from each other, apparently propelled along the surface of the nucleus by the lengthening bundles of microtubules between them.

Metaphase

Metaphase in an Animal Cell

Metaphase in a Plant Cell

Description The centosomes are now at opposite ends or poles, of the cell. The chromosomes convey on the metaphase plate, the plane the is equidistant between the spindles two poles The centromeres of all the chromosomes are aligned with one another at the metaphase plate For each chromosome, the kinetochores of the sister chromatids face opposite poles of the cell Thus, the iddentical chromatids of the cell are attached to kinetochores microtubules radiating from opposite ends of the cell The entire apparatus of nonkinetochore microtubules plus kinetochores microtubules is called the spindle because of its shape

Anaphase

Description Anaphase begins when the paired centromeres of each chromosome divide, liberated the sister chromatids from each other Each chromatid is now considered a full fledged chromosome. The spindle appparatus then begins moving the once joined sisters toward opposite poles of the cell. Because the kinetochore microtubules are attached to the centromere,, the chromosomes move centromere first. The kinetochere microtubles shorten as the chromosomes approach the cell poles. At the same time, the poles of the cell also move farther apart. By the end of anaphase, the two poles of the cell have equivalent and complete collections of chromosomes.

Telophase

Description Telophase, the nonkinetochore microtubules elongate the cell still more, and the daughter nuclei begin to form at the two poles of the cell where the chromosomes have gathered. Nuclear envelopes are formed from the fragments of the parent cell’s nuclear envelope and other portions of the endomembrane system. In a further reversal of prophase and prometaphase events, the nucleoli reappear and the chromatin fiber of each chromosomes becomes less tightly coiled. Mitosis, the equal division of one nucleus into two genetically identical nuclei, is now complete.