Biological Nanomachines

School of Physics and Astronomy

College of Engineering and Physical Sciences


Code 22176

Level of study Third/Final year

Credit value 10

Semester 2

Module description

Nature employs nanomachines to drive the fundamental processes of life inside living cells. Notable examples include the tiny nanomotors that drive cell movement, the pumps that transport ions across cell membranes, and the intricate machinery for processing DNA and RNA. These nanomachines are the 'shakers and movers' that dominate life on the nanometre scale.

How do nanomachines work? We'll see that the nanomotors in our muscles execute a biochemical cycle that is in some ways similar to the thermodynamic cycle of a macroscopic heat engine. However, a key difference is that nanomotors are tiny protein molecules that are in continuous random thermal motion. Just imagine what would happen if the pistons in a macroscopic motor, such as a car engine, moved at random! So, how can a nanomotor overcome its random motion to perform useful mechanical work?

To answer this question, the course will develop the key ideas that we need to understand the physics of biological nanomachines. Starting from the macroscopic idea of free energy in thermodynamics, we move on to Brownian motion, ratchets and the random walk, the kinetics of rate processes and transition-state theory.

We then consider the biological background of cells and biomolecules before turning to the nanomachines that operate inside living cells. You'll therefore learn some basic cell and molecular biology from a physicist's point of view. Along the way, you'll also see how physics allows us to perform neat experiments on single molecules.

Lecture Outline

1. Physical Background. Free energy and thermodynamics: polymer elasticity; reversible electric cells; biochemical reactions and equilibrium. Brownian motion and kinetics: diffusion, drift and the random walk; Maxwell's Demon and Feynman's ratchet; kinetics, chemically driven ratchets and transition-state theory.

2. Biological Background. Cells and biomolecules; proteins, enzymes & biosynthesis.

3. Biological Nanomachines. Cytoskeleton and cell movement; muscles; cilia and flagella; membranes, nerves and action potentials; energy generation and ATP synthase; DNA and RNA nanomachines (time permitting).