是构成遗传的基本单位；编码蛋白所有信息的DNA序列。从结构上来讲，基因包含三个区域：称为启动子的调节区域；与其并列的编码蛋白质的密码子区域；以及3'端尾部序列。在哺乳动物细胞里，启动子是一个包含着许多蛋白质结合位点的复杂区域，它调节基因的表达。单个基因可以被激活，由这些控制蛋白决定时间、地点及蛋白表达量，从而产生蛋白质。这一过程称为基因表达。在人类基因组中，大约有10万个基因。其中一些进化过程相关联而形成 "基因家族"表达相关蛋白。也有基因不再制造蛋白，这些进化中的残余物称为假基因。

The basic unit of heredity; the sequence of DNA that encodes all the information to make a protein. Structurally, a gene is formed by three regions: a regulatory region called the promoter juxtaposed to the coding region containing the protein sequence, and a “3’ tail” sequence. In mammalian cells, the promoter is a complex region containing binding sites for many proteins that regulate gene expression. A gene may be “activated” or “switched on” to make protein – this activation is referred to as gene expression - by these proteins which control when, where and how much protein is expressed from the gene. In the human genome, there are an estimated 100,000 genes. Some of these are evolutionarily related and form“gene families” that express related proteins. There are also genes that no longer make a protein; these defective remnants of evolution are called pseudogenes.