Seen in the upward spiral that branches follow around a tree trunk, the way leaves grow around a stem or the positioning of petals on a flower, the helix is arguably Nature’s favourite shape. Even biological molecules, from DNA to the protein in human hair, form neat coils (left), which make them strong and flexible. Biophysicists know that arranging molecules into shapes costs energy, and making a helix is relatively cheap. When they sliced vertically through the seemingly simple helix (centre), they discovered a familiar geometrical pattern. The design was similar to that of discs covering the surface of a cylinder (right). Many molecules, such as artificial carbon nanotubes, follow this arrangement since it is energetically as cheap as forming a helix and also very strong. The discovery is likely to help the new inter-disciplinary science of biomimetics, where the development of artificial materials is inspired by biological designs.
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.
BPoD is also available in Catalan at www.bpod.cat with translations by the University of Valencia.