Synchrony, the phenomenon where components of a system experience events in unison,  seems to be very common in biological systems. Temporal Clustering or Phase Synchrony,  a phenomenon related to synchrony, is where sub-groups (or cohorts) of components synchronize among themselves, but are out of phase with other cohorts. In bioreactor experiments on yeast metabolic oscillations we discovered a case where a culture of yeast exhibits temporal clustering in which two groups progress through their cell cycles  in anti-phase. In these experiments the cell cycle clusters and oscillations in the metabolism are seen to be tightly coupled. The discovery raises a number of mathematical questions such as: `What accounts for the difference  between a system that synchronizes and one that forms clusters?', `What determines the number of  clusters that appear?', and `How do individual cells distribute themselves among clusters?'. In this talk we will discuss how questions such as these can be studied mathematically using biologically motivated non-linear models and in many cases answers can be found. Biologically, the mechanism for the coupling between cell cycle and metabolism is puzzling. We propose a possible mechanism that relies on the fact that in the experiments the bioreactor is  operating near carrying capacity.