Question

Each human cell normally contains 23 pairs of chromosomes. Chromosome 1 is the longest and is approximately 247,200,000 basepairs in length.

(B) It actually takes 8 hours to replicate Chromosome 1. How many evenly spaced origins of replication would be needed to realize this rate of replication?

Answer 1

Origin of replication means the site or the space where the replication begins.Generally the replication are bidirectional but some times many replication site is seen in the same DNA.

The human replication speed is 50 nucleotide base per second.

So in 1 min=50*60=3000 bp

Now 8 hour=8*60=480 min

So in 8 hour a single replication fork can replicate 3000*480=1440000bp

Chromosome 1 base pair length is=2,47,200,000 bp which is replicated in 8 hour.

So the number of replication fork is= 2,47,200,000/1440000=171.6666667 or 172.

So almost 172 replication fork is needed to replicate the hole chromosome1 in 8 hour.