A brief review of replication, transcription and translation.Biotechnology: definition, history and ethical concerns. Roles of micro-organisms in biotechnology.Aspects of phage and bacterial genetics:viral lysogeny and lysisetc, phage inversion in Salmonella typhi, circularity of DNA; plasmid, transfer or mobility of genetic material,transposition and infectious drug resistance. Methods in molecular biology; (i) Polymerase chain reaction (applications in medical diagnosis, forensic investigations and molecular evolution)  (ii) DNA sequencing. Restriction enzymes and recombinant DNA technology.cDNA from mRNA expression in host cells. Novel proteins and site specific mutagenesis.Homologous recombination. Rec A protein and inducible DNA repair. Application of recombinant DNA for industrial and clinical purpose.Control of gene expression e.g. arabinoseoperon. Gene cloning: generation of gene fragments, methods used in producing recombinant fragments, recombinant screening and selection, use of mutagenic agents in gene transfer