Given that a chromosome is 60,000,000 bases in length, and DNA polymerase functions at a rate of 50 base pairs per second, what is the minimum number of origins of replication required on that chromosome to allow replication to complete if S phase lasts for 5.5 hours?
A)one
B)about 30
C)about 300
D)about 3000
E)about 30,000

Question

Quizplus · Accepted Answer

Given the length of the chromosome (60,000,000 bases) and the rate of DNA polymerase (50 base pairs per second), we can calculate the total time required to replicate the chromosome with a single origin of replication. First, convert 5.5 hours into seconds (5.5 hours * 3600 seconds/hour = 19,800 seconds). Since DNA polymerase works on both strands simultaneously, we divide the chromosome length by 2 to get 30,000,000 bases that need to be replicated from one origin. At a rate of 50 base pairs per second, a single origin can replicate 50 * 19,800 = 990,000 bases in 5.5 hours. To cover the entire 30,000,000 bases, we need 30,000,000 / 990,000 ≈ 30 origins of replication.

Given That a Chromosome Is 60,000,000 Bases in Length, and DNA