Microtubule dynamics with
polymerization, critical concentration,
and treadmilling.

This scientific illustration explains the polymerization and depolymerization dynamics of microtubules and their interaction with tubulin dimers. The graph in the first panel shows the relationship between total tubulin concentration (dimers and microtubules) and mass. The plot highlights the concept of critical concentration (Cc), where the polymerization of tubulin into microtubules begins. Below the threshold, tubulin remains in dimer form, and beyond it, microtubule mass increases.

The second panel depicts a microtubule with two distinct ends: the (+) end, which has a lower critical concentration and grows faster, and the (–) end, which is less stable due to its higher critical concentration. Arrows show the reversible addition and removal of tubulin dimers from both ends.

The final panel demonstrates the treadmilling effect, a dynamic process where tubulin dimers are added to the (+) end while being lost from the (–) end. Yellow segments highlight regions of active dimer turnover, illustrating the inherent instability and adaptability of microtubules in the cell.

This detailed illustration is perfect for use in cell biology textbooks, biochemistry journals, educational e-books, or scientific articles focusing on topics such as cytoskeletal dynamics, microtubule assembly, and intracellular transport.