Workout: Diffusion and random walks (Excel)

Read

Read the web page Diffusion and random walks.

Launch

To see how this works in practice, watch the video Monte Carlo simulation of random walk in Excel. In this video, the presenter uses an Excel spreadsheet to add random steps in the x-y direction to the position of a molecule. The result is a "random walk" path.

Answer these questions

1. What does the command "Rand()" in Excel do? Explain how the presenter was able to create a random number that was somewhere between -1 and 1.
2. Explain in your own words what is happening to the molecule and how the path is determined.
3. Create your own Excel spreadsheet to do this and make a lot of runs. Describe what you see. How often does the molecule follow a fairly straight path? Discuss the implications of this for a molecule released from a point in a cell – say a protein at a ribosome.

Joe Redish 10/14/17