Mitotic Cycle and Chromosome Reproduction

Abstract

In mitosis the genetic material of a cell is divided equally and exactly between two daughter cells. Each chromosome replicates in interphase, then divides into two daughter chromosomes, which segregate in anaphase and, with the other chromosomes of the set, form two daughter nuclei. In other words, the cells undergo a regular alternation of chromosome replication and segregation. The main features of mitosis are strikingly universal and may be observed throughout eukaryotes, from unicellular organisms to man. Figure 3.1 illustrates mitosis in untreated human lymphocytes. (Nowadays, only a few cytogeneticists have even seen human chromosomes that have not been treated with colchicine and hypotonic solution.) For comparison, Fig. 17.1 shows the last premeiotic mitosis in untreated pollen mother cells of the liliaceous plant, Eremurus (2n = 14).