What is a Gene Really?

Let’s Get Technical.

The definition of a gene that I grew up with was this:

A gene is a unit of heredity.

At the time, I had no inkling about the complexity of human biology, so I didn’t inquire further into what a unit of heredity meant. When I was in my college Genetics class, I learned that scientists don’t actually even fully agree on the definition of a gene.

Since there is no consensus, the strategy here will be to present a working definition of a gene which is both specific enough to give insight into general mechanism and leaves enough room to flexibly conform to context. Firstly, the definition must make sense in both the contexts of transmission genetics and molecular genetics. In other words, it must be veridical to the gene-phenotype relationship and be usable when exploring gene regulation at the molecular level. After extensive research, the definition that best satisfies the criteria above has been put forth by Professor Larry Moran, a biochemist at University of Toronto:

“A gene is a DNA sequence that is transcribed to produce a functional product.”

The first step is to understand both the conditions this definition imposes upon a gene and the flexibilities it allows. In doing so, the sufficiency of this definition will be advocated.