運用遺傳技術，通過識別其在一個或多個生物模型中的作用來認識新發現基因的功能。功能基因組用功能不明的分離基因作為起始點，然后選擇具有該同源基因的生物模型。這一生物模型可以是簡單的酵母細胞或復雜的線蟲甚至老鼠。基因被選擇性的用多種遺傳技術滅活，在此生物體上選擇性去除的效果被確定。通過這種方法去除基因，它對生物功能的貢獻就能夠被識別。功能基因組在評估和檢測新藥時十分有用。在另一種方法中，一整套基因被系統地滅活，人們就可以檢測其對特定細胞功能的影響。這里，一個新的基因和其功能就同時被識別了。

The use of genetic technology to determine the function of newly discovered genes by determining their role in one or more model organisms. Functional genomics uses as its starting point the isolated gene whose function is to be determined, and then selects a model organism in which a homolog of that gene exists. This model organism can be as simple as a yeast cell or as complex as a nematode worm, fruitfly, or even a mouse. The gene is selectively inactivated or "knocked out" using a variety of genetic techniques, and the effect of its selective deletion on that organism is determined. By knocking out a gene in this way, its contribution to the function of the organism (and, by implication, its function in man), can be determined. Functional genomics has proven particularly useful as a means of validating or testing novel therapeutic targets. In another approach, a whole set of genes may be systematically inactivated and the effect of this on a particular cellular function examined. Here, a new gene and its function are identified simultaneously.