The usefulness of theoretical models for the study of biological rhyth
ms is illustrated by considering several examples of oscillations resu
lting from different modes of cellular regulation, Considered in turn
are oscillations resulting from the regulation of enzyme activity, rec
eptor function, transport, and gene expression The generation of rhyth
mic behaviour by these various types of regulation is exemplified, res
pectively, by glycolytic oscillations in yeast cells, the periodic syn
thesis of cyclic AMP in Dictyostelium amoebae, intracellular calcium o
scillations, and circadian rhythms in Drosophila.