A mutant of yeast defective in cellular morphogenesis.

In the budding yeast Saccharomyces cerevisiae, each bud appears within a ring of chitin formed in the cell wall of the mother cell. Temperature-sensitive mutants defective in gene cdc24 synthesize chitin at restrictive temperatures, but do not organize it into the discrete rings found in normal cells, nor do they form buds. The chitin ring or an annular precursor structure may play an essential role in reinforcing the region of the cell wall involved in budding.