Images Dated 26th January 1998

Coloured TEM of genetically engineered plasmids

Gene splicing. Coloured transmission electron micrograph of genetically engineered DNA plasmids from the bacteria Escherichia coli. The plasmids (yellow) have had different gene sequences (various colours) spliced into them. Plasmids are symbiotic pieces of DNA (deoxyribonucleic acid) that occur in bacteria and yeast. They are separate from the main chromosome, replicate independently, and can be transferred from one cell to another carrying genes with them. This last property is exploited in genetic engineering. In gene therapy, plasmids with beneficial genes are inserted into human cells using viruses. Magnification: x43, 000 at 6x7cm size. x150, 000 at 8x10ins

© DR GOPAL MURTI/SCIENCE PHOTO LIBRARY