We tend to deal with properties of very large numbers of cells as if they were continuous functions. Actually, there is a broad spectrum of cell ages, and cell growth occurs as small increments that meld into smooth curves for anything that is measured. In other words, a single event for a cell is a tiny invisible blip for the many, many cells present. There are some natural situations in which cells become synchronized. Cells can all be stopped if darkness halts photosynthesis , and reillumination may start growth simultaneously. In the laboratory, restricted light or low temperature or some other factor can impair a step in division. The cells can be triggered to proceed together from that point with overall numbers that are stepwise with time.
Click to see sketches. This is termed a synchronous culture when all the cells divide simultaneously. The steps are seldom distinct for more than a few generations unless the triggering event continues to be applied periodically. Synchronous culture is an important case where differential equations are not appropriate.
Research with synchronous cultures has been very enlightening in terms of understanding what goes on in cells. One cell is far too tiny to be analyzed extensively, although there are techniques such as flow cytometry that provide some information as an individual cell passes through a laser beam. With synchronous culture, all the cells are the same age, and large samples analyzed by any technique, complicated or simple, can be translated to information about a single cell just by dividing by the number of cells in the sample. Concentrations of biochemicals during the life cycle of a cell have been studied in this manner.
How would you measure and plot on a graph the changes in a single cell from its birth to its division ?
Answer to question
Continue to simulation of synchronous culture
Dept. of Chemical Engr.