LONDON: Scientists have taken a big step toward designing complex forms of life from scratch by constructing five new artificial chromosomes of baker’s yeast, representing a third of the micro-organism’s genome, or genetic blueprint. The international team used computers to create laboratory-made versions of the threadlike structures that carry genetic code inside cells. Synthesizing genomes may alarm some who see biotechnologists “playing God” but scientists view it as a logical extension of existing genetic engineering that is already used routinely to make drugs like insulin, as well as genetically modified crops. The international group previously took seven years to build the first yeast chromosome in 2014. The addition of another five demonstrates accelerating progress in the field of synthetic biology, which promises a new era of designer life forms. New strains of synthetic yeast could be put to work to produce novel medicines, chemicals and biofuels. The work also serves as a foundation for a more ambitious project to synthesize a human genome in the next 10 years. Yeast is surprisingly closely related to humans at the genetic level, sharing 26 per cent of its genes with our species, although the human genome is around 250 times larger. While other teams have synthesized bacterial and viral DNA, the Synthetic Yeast Genome Project is the first to do this in a eukaryote, an organism whose cells contain a nucleus, like human cells. Writing in the journal Science on Thursday, scientists from the United States, China, Britain and France involved in the latest work reported that the yeast containing artificial genetic material was fit and healthy, just like normal yeast.