Some of the organisms that are used as highly informative models to study gene action and development. (a) Escherichia coli is a common bacterium; (b) Saccharomyces cerevisiae is a yeast; (c) the fruit fly Drosophila melanogaster and (d) Caenorhabditis elegans, a nematode, allow sophisticated studies of comparatively simple animal body plans; (e) Danio rerio, the zebrafish, and (f) Mus musculus, the laboratory mouse, represent more complex vertebrate model systems; (g) Arabidopsis was one of the first plant model organisms in genome projects. (a: CDC/Peggy S. Hayes; b: Photograph by Mansur. Released to the public domain, via Wikimedia Commons; c: Photograph by André Karwath. Licenced under CC-BY-SA-2.5, http://creativecommons.org/licenses/by-sa/2.5, via Wikimedia Commons; d: Photograph by Tormikotkas. Licensed under CC-BY-SA-3.0, http://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons; e: Photograph by Azul. Released to the public domain, via Wikimedia Commons; f: Steven Berger Photography, licensed under Creative Commons BY-SA 2.0; g: Photo by Peggy Greb, Agricultural Research Service, United States Department of Agriculture.) Source: Genetics: Unity and Diversity, Medical Genetics: An Integrated Approach Citation: Schaefer G, Thompson, Jr. JN. Medical Genetics: An Integrated Approach; 2017 Available at: https://accessmedicine.mhmedical.com/DownloadImage.aspx?image=/data/books/2247/schaefer_ch1_f011b-1.png&sec=173743745&BookID=2247&ChapterSecID=173743686&imagename= Accessed: October 28, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved