All multicellular organisms use cell division for growth and the maintenance and repair of cells and tissues.
Actively dividing eukaryote cells pass through a series of stages known collectively as the cell cycle: two gap phases (G1 and G2); an S (for synthesis) phase, in which the genetic material is duplicated; and an M phase, in which mitosis partitions the genetic material and the cell divides.
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G1 phase. Metabolic changes prepare the cell for division. At a certain point - the restriction point - the cell is committed to division and moves into the S phase.</span><span>
S phase. DNA synthesis replicates the genetic material. Each chromosome now consists of two sister chromatids.</span><span>
G2 phase. Metabolic changes assemble the cytoplasmic materials necessary for mitosis and cytokinesis.</span><span>
M phase. A nuclear division (mitosis) followed by a cell division (cytokinesis).</span></span>
The period between mitotic divisions - that is, G1, S and G2 - is known as interphase.
<span>Mitosis is a form of eukaryotic cell division that produces two daughter cells with the same genetic component as the parent cell. Chromosomes replicated during the S phase are divided in such a way as to ensure that each daughter cell receives a copy of every chromosome. In actively dividing animal cells, the whole process takes about one hour.</span>
Rock B may have many fossils.
