Animal cells have centrosomes. During the interval of cell division, two centrioles of centrosome each produce a new centriole, so there are two groups of centrioles in the cell. In the process of cell division, centriole in the two groups moves to the cell poles respectively. Numerous rays are emitted around the centrioles in the two groups, and the star rays between the centrioles in the two groups form spindle filaments. Plant cells directly form spindles without centriole.
At the end of animal cell division, the cell plate does not form in the middle of the cell, but the cell membrane sinks inward from the middle of the cell, and finally the cell divides into two parts, each of which contains a nucleus. In this way, a cell divides into two daughter cells. In the late stage of plant cell division, the cell plate forms and the middle part divides, so it is mainly in the late stage. Plants use spindles for mitosis, while animals use centrosomes for mitosis.
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Cell division refers to the proliferation of living cells and the process of their number splitting from one cell into two cells. Cells before division are called mother cells, and new cells formed after division are called daughter cells. It usually includes two steps: nuclear division and cytoplasmic division. In the process of nuclear division, the mother cell transfers genetic material to the daughter cell. Eukaryotic cell division includes mitosis, meiosis and amitosis.
Cytokinin can also prevent the leaves in vitro from aging and keep green, mainly because cytokinin can delay the degradation of chlorophyll and protein, stabilize polyribosomes (where protein synthesized at a high speed), inhibit the activities of deoxyribonuclease, ribonuclease and protease, and maintain the integrity of the membrane. Local application of cytokinin on leaves can attract other substances to transport and accumulate to the application site.
Prokaryotic cells have neither nuclear membrane nor nucleoli, but only a nuclear region composed of circular DNA molecules, also known as pseudonucleus, which has the function similar to that of nucleus. After that, the two intermediates gradually separated due to the growth of the interstitial membrane, and the two DNA molecular rings connected with them were pulled apart, and each DNA ring was connected with an intermediate. Between the two DNA rings that are pulled apart, the cell membrane grows towards the center, forming a diaphragm, and finally dividing a cell into two cells.