Genome packaging in a virus. (a) The tobacco mosaic virus has an RNA genome coiled inside a rod-shaped viral coat, packaged by RNA-binding proteins, as shown in an electron micrograph and molecular model. (b) A bacteriophage T2 particle was lysed and its DNA allowed to spread on the surface of distilled water in this electron micrograph. All the DNA shown here is normally packaged inside the phage head.