The basic courses of mitosis in a typical eukaryotic cell and unicellular red alga (C. merolae) cell. As typical cells contain many double membrane- and single membrane-bound organelles, they are not illustrated. During interphase, the centrosome (CEN) forms outside the nucleus (N), including the nucleolus (NLO; a). At prophase, the centrosome divides, and the resulting two asters can be seen to have moved apart. The chromosomes then condense; each chromosome consists of paired chromatids (CHR) attached by their kinetochores (KIN), the nuclear envelope breaks down, and the nucleolus dissolves (b). At metaphase, all the chromosomes align at the equator of the spindle (c). At anaphase, sister chromatids all separate synchronously and under the influence of microtubules, and the daughter chromosomes begin to move toward the poles (d). At telophase, the daughter nuclei and nucleolei reform using the contractile ring (CON); cytokinesis is almost complete (e). Phase contrast-fluorescent images of C. merolae interphase (f) and dividing cells (g–j) showing localization of nuclear (N), mitochondrial (M), and plastid DNA (P in blue/white) after 4′,6-diamidino-2-phenylindole staining are shown. The plastids emit red autofluorescence. Division of the plastid, mitochondrion, and nucleus occur in this order (f–j). During late G2 (f) and prophase (g), the plastid and mitochondrial divisions advance and finish by the metaphase (h). At anaphase, the chromatids begin to move toward the poles, but each chromatid cannot be identified (i). Chromosomes do not condense during mitosis. Cytokinesis starts from the plastid side and closes between daughter nuclei (j). Scale bar in j = 1 μm. Schematic representation of C. merolae interphase (k) and dividing cells (l–o) containing single membrane-bound organelles (ER, a Golgi apparatus [G], lysosomes [LY], and a microbody [MI]) and double membrane-bound organelles (a nucleus [N], a mitochondrion [M], and a plastid [P]). The nucleus has a nucleolus (NLO), while the mitochondrion and plastids contain mitochondrial and plastid nuclei (nucleoids) in the center (blue), respectively. During interphase, the centrosome forms the focus for the interphase microtubule array outside the nucleus (k). By early prophase, the centrosome and Golgi apparatus divide, and the resulting two asters and Golgi apparatus can be seen to have moved apart (l). Chromosomal condensation does not occur during prophase. At prometaphase, the nuclear envelope does not break down. Plastid and mitochondrial divisions start in this order in late G2 and end by metaphase. The dynamic trio (FtsZ ring, MD/PD rings, and dynamin ring) controls mitochondrial and plastid divisions. The outer MD ring (red ring in l) and outer PD ring (green in l) are illustrated at the equator of a dividing V-shaped mitochondrion and dumbbell-shaped plastids, respectively (l). Microbody and lysosomes associate with the dividing V-shaped mitochondrion (l). At metaphase and early anaphase, the bipolar structure of the spindle is clear, and all chromosomes appear to be aligned at the equator of the spindle (l). But each chromosome cannot be identified (l). Plastid and mitochondrial divisions finish by metaphase, at which time division of the microbody starts (l). The connecting bridge (arrow in n) between daughter mitochondrion and a microbody appears to play an important role in microbody division. At anaphase, sister chromatids separate synchronously, and daughter chromosomes begin to move toward the poles. Chromosomal condensation never occurs during mitosis in C. merolae. At telophase, the daughter nuclei and nucleoli reform, and division of the microbody might occur through the connecting bridge. By late telophase, cytokinesis is almost complete (o). The mitochondrion, lysosome, and microbody behave as if they are linked. At the final stage of cell division, a tiny contractile-like ring appears at the equator of the cell.