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The Immune System Piercing a Bacterial Cell Wall
Our blood contains proteins that recognize and destroy invading cells and viruses. This illustration shows a cross section through a bacterial cell wall (lower half, in greens, blues and purples) being attacked by proteins in the blood serum (at the top, in yellows and oranges). Y-shaped antibodies begin the process by binding to the surface of the cell, and are in turn recognized by the six-armed protein at upper center. This begins a cascade of actions that ultimately lead to the formation of a membrane attack complex, shown here piercing the cell wall of the bacterium (1,000,000 X).
