1. Can you think of any other mechanisms besides topoisomerase activity that could release supercoiling in replicating DNA? 2. In developing sea urchins, just after fertilization, the cells divide...

1. Can you think of any other mechanisms besides topoisomerase activity that could release supercoiling in replicating DNA?

2. In developing sea urchins, just after fertilization, the cells divide every 30–40 min. In the adult, the cells divide once every10–15 h. The amount of DNA per cell is the same in each case, but the DNA obviously replicates much faster in developing cells. Propose an explanation to account for the difference in replication time.