English: This painting shows a cross-section through an Escherichia coli cell. The characteristic two-membrane cell wall of gram-negative bacteria is shown in green, with many lipopolysaccharide chains extending from the surface and a network of cross-linked peptidoglycan strands between the membranes. The genome of the cell forms a loosely-defined "nucleoid", shown here in yellow, and interacts with many DNA-binding proteins, shown in tan and orange. Large soluble molecules, such as ribosomes (colored in reddish purple), mostly occupy the space around the nucleoid.