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 made of proteins. The capsid has gp24* protein pentamers (cyan) at 11 of the 12 vertices of the icosahedron, with gp23* proteins (pink hexamers) surrounding a Hoc protein (red) forming the faces. There is one gp20 protein at the vertex that joins to the long tail. 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.