How long does mitosis take

The final steps of chromosome segregation and especially decatenation of the two circular chromosomes occurs during G2 phase. Adapted from M. Laub et al. Arguably the best-characterized prokaryotic cell cycle is that of the model organism Caulobacter crescentus. One of the appealing features of this bacterium is that it has an asymmetric cell division that enables researchers to bind one of the two progeny to a microscope cover slip while the other daughter drifts away enabling further study without obstructions.

In this case, the cell-cycle progression goes hand in hand with the differentiation process giving readily visualized identifiable stages making them preferable to cell-cycle biologists over, say, the model bacterium E. The behavior of mammalian cells in tissue culture has served as the basis for much of what we know about the cell cycle in higher eukaryotes.

The eukaryotic cell cycle can be broadly separated into two stages, interphase, that part of the cell cycle when the materials of the cell are being duplicated and mitosis, the set of physical processes that attend chromosome segregation and subsequent cell division. The rates of processes in the cell cycle, are mostly built up from many of the molecular events such as polymerization of DNA and cytoskeletal filaments whose rates we have already considered.

The stage most variable in duration is G1. In less favorable growth conditions when the cell cycle duration increases this is the stage that is mostly affected, probably due to the time it takes until some regulatory size checkpoint is reached. Though different types of evidence point to the existence of such a checkpoint, it is currently very poorly understood.

Historically, stages in the cell cycle have usually been inferred using fixed cells but recently, genetically-encoded biosensors that change localization at different stages of the cell cycle have made it possible to get live-cell temporal information on cell cycle progression and arrest.

Figure 2: Cell cycle times for different cell types. Each pie chart shows the fraction of the cell cycle devoted to each of the primary stages of the cell cycle. As we discussed in the previous section, the lengths of G1 and G2 vary in cells based on the individual cell's level of preparedness for proceeding in the cell cycle.

Remember, cells can enter G0 for extensive amounts of time during G1 before continuing on to S phase. If a cell has quickly undergone sufficient cell growth or DNA replication, the time spent in G1 and G2 will be decreased. G1 is typically the longest phase of the cell cycle. This can be explained by the fact that G1 follows cell division in mitosis; G1 represents the first chance for new cells have to grow. Cells usually remain in G1 for about 10 hours of the 24 total hours of the cell cycle.

The length of S phase varies according to the total DNA that the particular cell contains; the rate of synthesis of DNA is fairly constant between cells and species. Usually, cells will take between 5 and 6 hours to complete S phase. G2 is shorter, lasting only 3 to 4 hours in most cells.

In sum, then, interphase generally takes between 18 and 20 hours. Estimates for the duration of the G1 and G2 stages were 6. In accordance with this, the duration of the whole mitotic process was 8. After 60 min, label was in late prophase, after min, in mid telophase and after min, in late telophase. We conclude that there is overlap between some mitotic phases and cycle stages.