![Twisted molecular chain and helical coil simple diagram.](http://static.sciencelearn.org.nz/images/images/000/003/395/full/WOOL_ITV_FibreStrustureAndProps_TwistedMolecularChainHelicalCoil_edited.jpeg?1674170710)
Within the twisted molecular chains are protein chains that are coiled in a helical shape much like a spring. This structure is stiffened by hydrogen bonds and disulphide bonds within the protein chain. They link each coil of the helix, helping to prevent it stretching. The helical coil – the smallest part of the fibre – gives wool its flexibility, elasticity and resilience, which helps wool fabric keep its shape and remain wrinkle-free in use.
Image: The University of Waikato Te Whare Wānanga o Waikato