Cytochrome C (image) Washington University in St. Louis Caption The cytochrome c protein (colored ribbons), holds in its embrace a heme group (white honeycomb) that in turn clasps an iron atom (orange ball). This molecule is essential to life and any chemical that interferes with its activity is lethal. Credit Resource for Biocomputing, Visualization, and Informatics at the University of California, San Francisco. Usage Restrictions None 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.