ABSTRACT
Among Eukarya, the cell cycle is more elaborate, because it includes mitosis (Figures 7.3 and 7.4). Again, there is a G1 phase where cells are usually diploid, although there are many types of cells (e.g., in fungi) that are normally haploid in G1 (i.e., most fungi undergo haploid cell cycles for most of their life cycles). The cells proceed through the S phase, where the DNA is completely replicated, and on to G2, where cells are tetraploid if they started as diploid, or diploid if they started as haploid. Finally, they proceed through mitosis (Figures 7.4 and 7.5), which includes a prophase, where the chromosomes condense; prometaphase, where the microtubules polymerize and the nuclear membrane disintegrates; metaphase, when the chromosomes are lined up in the middle of the cells; anaphase, where the chromatids separate to become chromosomes; telophase, where the chromosomes decondense and the nucleus is reconstructed; and finally cytokinesis, where the cytosol divides to produce two daughter cells.
