A model organism is a species that biologists choose to study, not necessarily because it has any inherent medical, agricultural, or economic value, but because it has certain traits that make it easy and convenient to work with. Studying model organisms enables researchers to perform experiments that might be impossible to carry out, due to logistical, financial, or ethical constraints, on organisms of more practical interest, such as humans.

This approach has been tremendously successful in the fields of genetics and molecular and cellular biology because, at their most fundamental levels, biological processes are remarkably similar across species. For example, the genetic code and much of the cellular machinery responsible for replication, transcription, translation, and gene regulation are essentially identical in all eukaryotic organisms. In many cases, genes have even been demonstrated to be functionally interchangeable between humans and baker's yeast.

Among the most commonly studied...