  Many intracellular processes continue to oscillate during the cell cycle.
Although it is not well-understood how they are affected by discontinuities in
the cellular environment, the general assumption is that oscillations remain
robust provided the period of cell divisions is much larger than the period of
the oscillator. Here, I will show that under these conditions a cell will in
fact have to correct for an additional quantity added to the phase of
oscillation upon every repetition of the cell cycle. The resulting phase shift
is an analogue of the geometric phase, a curious entity first discovered in
quantum mechanics. In this Letter, I will discuss the theory of the geometric
phase shift and demonstrate its relevance to biological oscillations.
