运用遗传技术，通过识别其在一个或多个生物模型中的作用来认识新发现基因的功能。功能基因组用功能不明的分离基因作为起始点，然后选择具有该同源基因的生物模型。这一生物模型可以是简单的酵母细胞或复杂的线虫甚至老鼠。基因被选择性的用多种遗传技术灭活，在此生物体上选择性去除的效果被确定。通过这种方法去除基因，它对生物功能的贡献就能够被识别。功能基因组在评估和检测新药时十分有用。在另一种方法中，一整套基因被系统地灭活，人们就可以检测其对特定细胞功能的影响。这里，一个新的基因和其功能就同时被识别了。

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.