Mycoplasma genitalium, transmission electron micrograph (TEM). M. genitalium has the smallest genome (total genetic material) of all living organisms. Its genome was mapped in 1993, making it the second complete bacterial genome to be sequenced. In January 2008, a team at the J. Craig Venter Institute, USA, used this map to make a synthetic bacterial chromosome, called M. laboratorium, from scratch. A chromosome is made up of proteins and DNA (deoxyribonucleic acid). DNA contains sections (genes) that encode the cell's structure and function. The new chromosome, containing only the genes needed for life, was then inserted into a M. genitalium bacterium with its genome removed. Having a different chromosome changes the bacterium's function, making it different from wild M. genitalium bacteria. Magnification: x43,000 when printed 10cm wide.