For over a century, research scientists have studied experimental, or model, organisms to examine the mechanisms of inheritance and development. In more recent times, researchers have analyzed the molecular biology and biochemistry of experimental organisms to gain knowledge of gene function. Sequencing of various genomes has revealed that many genes in bacteria and multicelled organisms are very similar to the human counterparts. Experimental organisms useful for study because much is known of their behavior and genetic composition. Their ease of handling, short life span (which permits the examination of many generations in a short time), and underlying similarity with human processes permits relatively easy study and manipulation in order to gain insight of various developmental or disease processes. For instance genetics is easier in small organisms that breed quickly than in larger organisms, such as humans. However, various underlying aspects of their biological processes are similar...