Membrane biophysics: The dynamics of growing axons

We know an enormous amount about the chemistry of a living cell, but next to nothing about its physics — the interplay of forces between organelles and molecules that governs the cell’s detailed behaviour. Think of the plasma membrane, for example: an oily sea of phospholipid molecules studded with protein ‘icebergs’ of different shapes and sizes, some floating free and others anchored at their base. How does this molecular goulash behave when the cell moves or changes its shape? If a lipid tide flows in one direction, will this carry with it the protein icebergs? What forces must be overcome if the sea has to increase in area or deform its contours? Questions such as these are still beyond our reach, but a raft of novel techniques using the light microscope brings at least the promise of quantitative answers.