5: Transgenesis Check Access

Transgenesis is a term to describe an array of techniques used to modify the genomes of intact organisms including those of plants, insects, invertebrates, amphibians, fish and small and large mammals. To increase our knowledge of human health and disease, it is essential that we elucidate the function of the 21 000 genes in the mammalian genome. The mouse is the most commonly used mammalian model in which to explore gene function owing to the relative ease with which its genome can be modified. In the mouse, gene function can be altered in a number of ways, including over-expressing a gene, expressing a foreign gene, knocking out or deleting single or multiple genes, introducing point mutations and altering gene expression in a specific tissue or at a specific point in time. This chapter describes how the different techniques are used to introduce this wide range of gene modifications.