Silk
Key O = Oxygen atoms N = Nitrogen atoms Unlabelled corners and ends = Carbon atoms H = Hydrogen atoms (Further hydrogens are attached to all carbons, so as to make all carbons have four bonds)
This diagram shows two repeat units of the protein in natural silk, known as ‘fibroin’, joined end-to-end. A real silk fibre would have over 100,000 of these all joined together in one chain, just as the two shown here are, and one fibre would have hundreds of these long molecules, all bundled together. This is what gives silk its strength.