 One such example is the D1 proteins which replace the host cells D1 protein when it becomes damaged.The virus up-regulates photosynthesis, which leads to an increased rate of D1 protein degradation, the host cell alone can not efficiently replace these proteins so the cyanophage replaces them for the host cell, allowing it to continue providing energy for the cyanophage replication cycle.It is evident that cyanophage replication is heavily dependent on the diel cycle.