# A mechanical model of bacteriophage DNA ejection

## TL;DR

This paper presents a mechanical model demonstrating the exponential scaling of DNA ejection mobility in bacteriophages, illustrating the capstan mechanism's role in DNA packaging and ejection.

## Contribution

It introduces a scaled-up mechanical model that replicates the DNA ejection scaling observed in experiments, providing a tangible demonstration of the capstan mechanism.

## Key findings

- Model exhibits exponential scaling similar to biological phages
- Demonstrates the capstan mechanism as a key factor in DNA ejection
- Provides a visual and experimental analogy for DNA packaging forces

## Abstract

Single molecule experiments on bacteriophages show an exponential scaling for the dependence of mobility on the length of DNA within the capsid. It has been suggested that this could be due to the "capstan mechanism" -- the exponential amplification of friction forces that result when a rope is wound around a cylinder as in a ship's capstan. Here we describe a desktop experiment that illustrates the effect. Though our model phage is a million times larger, it exhibits the same scaling observed in single molecule experiments.