Synthesis of artificial genes - a method in the field of synthetic biology , which is used to create artificial genes in the laboratory. Currently based on solid phase DNA synthesis. Its difference from molecular cloning ( recombinant DNA ) and polymerase chain reaction (PCR) is that for the method there is no need to use pre-existing DNA sequences . Thus, fully synthetic double-stranded DNA molecules can be made without any restrictions on any nucleotide sequence or size. This method was used to create functional bacterial or yeast chromosomes containing about one million base pairs. Recent studies also suggest the possibility of creating new nucleotide pairs in addition to two pairs of natural bases, which could significantly increase the possibilities for expanding the genetic code.