Mechanical Properties of DNA Replication

Central to the function of cellular life is the reading, storage and replication of DNA. Due to the helical structure of DNA, a complicated topological braiding of new strands follows the duplication of the old strands. Even though this was discovered over 60 years ago, the mathematical and physical questions this presents have largely gone unaddressed. In this letter we construct a simple idealized model of DNA replication using only the most basic mathematical and mechanical elements of DNA replication. The aim of this is to reveal the mechanical balance of braided, replicated DNA against the twist of unreplicated DNA at the heart of the replication process. The addition of topoisomerase action is included presenting a balancing force offering a glimpse into the ways in which cells maintain this balance. Additionally the physical basis for recently observed replication/replication and replication/transcription conflicts are examined showing how gene orientation and size can impact DNA replication.