Question

If a eukaryotic chromosome has 25 origins of replication, how many replication forks does it have at the beginning of DNA replication?

Short answer

The eukaryotic chromosome has 50 replication forks at the beginning of DNA replication.

Step-by-step solution

Understand Origins of Replication

An origin of replication is a particular sequence in a genome at which replication is initiated. In the eukaryotic chromosome, each origin of replication forms a bubble and replication occurs in both directions using both strands of the DNA.

Understand Replication Forks

In each replication bubble, there are two ends where the DNA is being unwound. These are called replication forks. Each origin of replication has two replication forks.

Calculate the number of Replication Forks

Since each origin of replication has two replication forks, to find the total number of forks we multiply the number of origins by two. Given 25 origins of replication, \[ 25 \text{ origins} \times 2 \text{ forks/origin} = 50 \text{ forks} \].