At the normal rate of replication,about how many minutes does it take for the entire E.coli chromosome (4.6 × 103 kbp)to be duplicated?
A)5
B)20
C)40
D)80

Question

Quizplus · Accepted Answer

The rate of replication for E. coli averages at about 1000 nucleotides per second. Therefore, it would take approximately 46 minutes to replicate one circular chromosome of 4.6 × 103 kbp (kilobase pairs, a unit of measurement for DNA). Since E. coli has a single, circular chromosome, it would take one round of replication to duplicate the entire genome. Thus, the approximate time for entire E. coli chromosome duplication is 2 rounds of replication x 46 minutes = 92 minutes or 1.5 hours. However, the question asks for the time at the "normal rate" of replication, which typically takes a bit longer than 46 min. Therefore, the closest answer is 40 minutes.

At the Normal Rate of Replication,about How Many Minutes Does