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Figure 1: Schematic of the cell cycle. outer ring: I = Interphase, M = Mitosis; inner ring: M = Mitosis, G 1 = Gap 1, G 2 = Gap 2, S = Synthesis; not in ring: G 0 = Gap 0/Resting. Replication timing refers to the order in which segments of DNA along the length of a chromosome are duplicated.
The mitosis process in the cells of eukaryotic organisms follows a similar pattern, but with variations in three main details. "Closed" and "open" mitosis can be distinguished on the basis of nuclear envelope remaining intact or breaking down. An intermediate form with partial degradation of the nuclear envelope is called "semiopen" mitosis.
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.
G 1 phase together with the S phase and G 2 phase comprise the long growth period of the cell cycle cell division called interphase that takes place before cell division in mitosis (M phase). [1] During G 1 phase, the cell grows in size and synthesizes mRNA and protein that are required for DNA synthesis. Once the required proteins and growth ...
As DNA synthesis continues, the original DNA strands continue to unwind on each side of the bubble, forming a replication fork with two prongs. In bacteria, which have a single origin of replication on their circular chromosome, this process creates a "theta structure" (resembling the Greek letter theta: θ). In contrast, eukaryotes have longer ...
Synthesis (S), in which the cell synthesizes its DNA and the amount of DNA is doubled but the number of chromosomes remains constant (via semiconservative replication). G 2 (Gap 2), in which the cell resumes its growth in preparation for division. The cell continues to grow until mitosis begins. In plants, chloroplasts divide during G2.
Cell division in prokaryotes (binary fission) and eukaryotes (mitosis and meiosis). The thick lines are chromosomes, and the thin blue lines are fibers pulling on the chromosomes and pushing the ends of the cell apart. The cell cycle in eukaryotes: I = Interphase, M = Mitosis, G 0 = Gap 0, G 1 = Gap 1, G 2 = Gap 2, S = Synthesis, G 3 = Gap 3.
Mitotic DNA synthesis (MiDAS) is a process of irregular DNA replication where DNA synthesis, naturally occurring in the S phase, takes place in the M phase of the cell cycle. Mitotic DNA synthesis is known to occur when cells are experiencing stress related to DNA replication . [ 151 ]