Animation showing the structure of a T4 bacteriophage virus as it is built up component by component. The virus comprises a double-stranded DNA genome (red) enclosed in an icosahedral capsid (blue) made of proteins. The capsid has gp24* proteins at 11 of the 12 vertices of the icosahedron, with gp23* proteins forming the rest of the structure and one gp20 protein at the vertex that joins to the long tail. The capsid also contains hoc and soc proteins. During the phage's infection of an Escherichia coli bacterium, it binds to the surface using its six tail fibres, then, injects its DNA genome through the gp23* protein and through the tail and baseplate into the bacterium.