Concatemers of differentially expressed multiple genes

Concatemers of concatenated expression cassettes and vectors that enable the synthesis of such concatemers are disclosed. The main purpose of these concatemers is the controllable and co-ordinated expression of large numbers of heterologous genes in a single host. Furthermore, described are concatemers of cassettes of nucleotide sequences and a method for preparing the concatemers. In a further aspect, transgenic host cells comprising at least one concatemer are described, as well as to a method for preparing the transgenic host cells. Finally, a vector is described comprising a cassette of nucleotides, a method for preparing the vector, a nucleotide library comprising at least two primary vectors each comprising a cassette of nucleotides, and a method for preparing the library.