Question

Which statement is not true about DNA replication?

• A. It proceeds in a 5-to-3 direction only
• B. One strand of new DNA is replicated faster than the other strand at the replication fork
• C. DNA can only replicate at one point on a chromosome at one time
• D. Replication can only begin at a special origin of replication

Answer 1

Answer: (C)

DNA can only replicate at one point on a chromosome at one time

Replication occurs simultaneously at multiple places along a DNA strand because human DNA is very long (with up to 80 million base pairs in a chromosome). It unzips at multiple places along its length so that the replication process is going on simultaneously at hundreds of places along the length of the chain. In humans, DNA is copied at about 50 base pairs per second. The process would take a month (rather than the hour it actually does) without these multiple places on the chromosome where replication can begin.

So, the correct option is 'DNA can only replicate at one point on a chromosome at one time'.