A Bacteriophage (image) University of Arizona Caption Bacteriophages come in different shapes and sizes. This one has a "head" containing the virus' DNA and a "tail" with which it attaches to bacterial cells when it infects them. The scale bar in this electron microscope image is about one thousandth the diameter of a human hair. Credit Natalie Solonenko Usage Restrictions This visual may only be used in conjunction with reporting/posting of this news release. Image/video credit must be included exactly as indicated. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.