Shape changes in molecules

A single molecule can assume different three-dimensional shapes without breaking any of the covalent bonds between its atoms, as shown in (a) for a six-carbon molecule. Hydrogen atoms above the blue plane are shown in white; those below the blue plane are blue. (b) Two molecules are shown schematically as having complementary shapes that permit them to interact. When interacting, the flexible nature of the molecules causes molecule 2 to twist sufficiently to assume a new shape. This change in shape is often an important mechanism by which one molecule influences the activity of another.