Figure 1.

The synthetic biology test cycle. (From top, clockwise) Synthetic DNA constructs are designed and manipulated using computer-aided design software. The designed DNA is then divided into synthesizable pieces (synthons) up to 1–1.5 kbp. The synthons are then broken up into overlapping single-stranded oligonucleotide sequences and chemically synthesized. The oligonucleotides are then assembled together into the designed synthons using gene synthesis techniques. If necessary, multiple synthons can be assembled together into larger DNA assemblies or devices. The assembled DNAs are then typically cloned into an expression vector and sequence-verified. Once verified, the synthetic constructs are transformed into a cell and the function of the synthetic construct is assayed. Depending on the results the constructs can then be modified or refined and the test cycle is repeated until a DNA construct is obtained that produces the desired function.