go, to observe where the cell is located in each of the overlapping
I + C + D sequences. At the end of the first I period, the
chromosome initiates replication, as indicated by a small filled
circle at the left end, and preparation begins for the next initiation
event as shown in the second I + C + D sequence. After
20 min of the first C period, the chromosome is half replicated.
After 35 min of the first C period, the chromosome is 35/40
replicated and new rounds of replication have initiated due to
the second sequence, as indicated by two filled circles at the
left end. Thus, the cell has begun to progress through two C
periods simultaneously. Replication along the first sequence ends