DNA Replication Watson and Crick discovered the double helix structure and raised the question of how DNA was replicated. After many generations, all DNA in the cell was heavy. The cells were placed in regular medium with N 14 and were allowed to grow. They followed the DNA for two generations as shown in the figure here. Semi-Conservative Their results supported semiconservative replication as the correct model.
Replication occurs as the result of the enzyme DNA polymerase .
As the DNA strands pull apart, the DNA polymerase moves along the template strand adding new base pairs to the strand being synthesized. When the strands denature in a given segment of DNA, a replication bubble is formed, having two replication forks at the ends where the strands continue coming apart. The point where replication begins is also known as the origin of replication . However, in eukaryotic cells, there is so much DNA that many different origins of replication are needed to be able to replicate all the DNA in the necessary time frame. When a DNA from one origin catches up to the DNA from another origin, they are joined an enzyme called a ligase .