The organisation of the genomes of higher organisms derived mainly from the application of recombinant DNA technology and related techniques. Methods used for the isolation, identification and characterisation of eukaryotic genomes in terms of the organisation of single copy and repeated sequences and of coding and non-coding sequences and of several gene clusters, e.g. the alpha and beta globin gene cluster. Mechanisms regulating eukaryotic gene expression, at the level of transcription RNA processing and translation including siRNA –mediated control. Review of several specialised genetic systems in plants and animals such as mitochondria, chloroplasts and RNA and DNA tumour viruses.