4.10 - Genetic engineering

4.10 — From genome to characteristic

A genome is all the genetic material of an organism. A gene is a section of DNA that carries the instructions for making a particular protein. The action of that protein can contribute to a characteristic of the organism.

Genetic engineering works at this molecular scale. Scientists deliberately modify an organism's genome, for example by introducing a selected gene. If the introduced gene is expressed, the cell makes the corresponding protein. The protein's action can then give the organism a new desirable characteristic, meaning a characteristic intended for a particular purpose.

An organism whose genome has been altered using genetic engineering is a genetically modified organism, or GM organism. The inserted gene is neither the protein nor the characteristic. Keep the causal route clear:

gene introduced into genome -> gene expressed -> protein produced -> protein action contributes to characteristic

The organism does not acquire the characteristic because it needs it. Genetic engineering is also different from selective breeding: selective breeding chooses parents and combines alleles already present in those parents, whereas genetic engineering changes genetic material directly using laboratory techniques.