How Do Yeast Grow?
Both haploid and diploid yeast cells divide by budding (see Figure 2). The cell division cycle begins with a single, unbudded cell (Pringle & Hartwell 1981; Byers 1981). This cell buds, the bud grows to nearly the size of the parent cell, the nucleus divides, and the two cells separate into two unbudded cells. The cycle then begins again for both of the cells. The result is an exponential increase in the number of cells with a doubling time equal to the mean cell-division-cycle time. This varies with the strain, the growth medium, and the temperature, but can be as short as one hour. At this rate, a single cell can grow into a barely visible colony in one day. The growth behavior of yeast cultures is similar to that of bacteria. When a growth medium is inoculated, the cells require a period of preparation before they start dividing. Following this lag period which may be up to several hours they rapidly enter the exponential phase during which their number and mass double at equal time
