Synthetic Biology

Synthetic biology uses chemically synthesized DNA sequences rather than recombining existing DNA, distinguishing it from recombinant DNA technology. Unlike genetic engineering, which transfers individual genes between organisms, synthetic biology constructs novel biological systems. Genome editing makes small changes to an organism's DNA, while synthetic biology inserts large artificially synthesized sequences coding for multiple genes into genomes.

DNA sequencing and chemical DNA synthesis are crucial to synthetic biology. Sequencing studies genetic material from organisms found in nature, while chemical synthesis builds newly designed sequences for testing. Together, these techniques allow scientists to analyze natural genomes and create novel synthetic sequences that do not exist in nature.

Scientists redesigned Saccharomyces cerevisiae by inserting bacterial and plant genes into its genome to produce a precursor to artemisinin, an inexpensive anti-malarial drug. This genome redesign involved introducing large stretches of artificially synthesized sequences coding for multiple genes. The project demonstrates how synthetic biology solves specific problems by combining genetic material from different organisms.

Mycoplasma genitalium was selected for artificial genome synthesis because it has one of the smallest bacterial genomes with approximately 485 genes encoded in 6,000,000 base pairs. Scientists eliminated about 100 non-essential genes to create a minimal synthetic genome. The successful synthesis of M. genitalium's artificial genome in 2008 represented a major breakthrough in constructing completely new synthetic genomes.

Scientists created a synthetic single-celled organism using an artificially synthesized genome sourced from Mycoplasma mycoides. Although M. mycoides has a larger genome than M. genitalium, it was chosen for faster growth rate. The synthetic genome was constructed by chemically synthesizing small DNA cassettes, assembling them into subassemblies, and linking them using homologous recombination, a natural DNA repair mechanism.

Golden rice is a genetically modified rice plant producing grains rich in β-carotene, a vitamin A precursor. Rice plants naturally produce β-carotene only in leaves because production pathways are turned off in grains. Synthetic biology enabled golden rice by inserting three genes encoding phytoene synthase, phytoene desaturase, and lycopene β-cyclase into the rice genome, triggering β-carotene production in grains.

Synthetic biology enables diverse applications including protein and enzyme production, bioremediation, value-added macromolecule production, and adding desirable traits to crops. By constructing novel biological components and systems that do not exist in nature, scientists can address practical problems in medicine, agriculture, and environmental remediation. These applications demonstrate synthetic biology's interdisciplinary approach combining engineering with molecular and systems biology.