DNA SHAPE is a term used to describe the physical structure of DNA molecules. The three most common shapes are SPIRAL, HELIX, and COIL. A SPIRAL shape has six letters and is formed when two strands of DNA twist around each other in a corkscrew-like pattern. A HELIX shape has five letters and is formed when two strands of DNA wrap around each other in a double HELIX structure. A COIL shape has four letters and is formed when DNA strands twist and fold back on themselves.