Lambda bacteriophages. Coloured transmission electron micrograph (TEM) of a section through two lambda bacteriophages. Bacteriophages (phages) are viruses that infect bacterial cells. These lollipop-shaped viruses have a head (red) containing the genetic material and a tail (pink). Lacking any reproductive machinery of their own, bacteriophages commandeer the bacteria's cellular apparatus, making the bacteria produce more bacteriophages. Phages of human faecal bacteria can cause malabsorption in the small intestine due to release of toxic chemicals from dead bacteria. Magnification: x63,000 at 35mm size.