DNA can be made from artificial sources, if mRNA is purified then an enzyme called reverse transcriptase can reconstruct the DNA sequence for the protein, the gene. The gene lacks the promoter region required for mRNA synthesis. This problem can be over come by joining the sequence to a complete bacterial gene, so that the two are expressed together. Value of genetic engineering Genes placed in microbes can produce large quantities of use full products e.g. insulin engineered genes can be placed within plants and animals to improve traits such as growth rate or the quality of protein produced. Recent developments include the introduction of insecticide genes into plants to reduce the need for spraying.
Gene therapy involves putting genes into humans to cure genetic disease.
Work is being carried out on diseases such as Cystic fibrosis.