The E.coli chromosome is 1.28 mm long. Under optimal conditions the chromosome is replicated in 40 minutes. a) Explain what is the distance traversed by one replication fork in 1 minute? b) If replicating DNA is in the B form 10.4 base pairs per turn, explain how many nucleotides are incorporated in one minute in one replication fork? c) If cultured human cells such as HeLa cells replicate 1.2m of DNA during a 5- hour S phase as well as at a rate of fork movement one-tenth of that seen in E. coli, explain how many origins of replication must the cells contain? d) Explain what is the average distance, in kilobase pairs between these origins?