The invention provides methods of synthesizing a product DNA molecule having a desired and/or defined sequence. The methods involve annealing at least one long oligonucleotide and at least one short oligonucleotide to at least one anchor strand having a sequence at least partially complementary to the at least one long and at least one short oligonucleotide. After annealing, at least one long oligonucleotide bound to an anchor strand abuts at least one short oligonucleotide bound to the same anchor strand. The anchor strand has one or more non-standard nucleotides, and optionally one or more degenerate nucleotides. The method involves ligating the abutting at least one long oligonucleotide and at least one short oligonucleotide to form a dsDNA molecule. The invention also provides methods of synthesizing DNA molecules by assembling oligonucleotide members of a library that contains less than 20,000 members that can be assembled into all possible DNA sequences.

The methods of the disclosure can be used to enrich a population of circular polyribonucleotides in a mixture of linear polyribonucleotides and circular polyribonucleotides.

The invention provides methods of synthesizing a product DNA molecule having a desired and/or defined sequence. The methods involve annealing at least one long oligonucleotide and at least one short oligonucleotide to at least one anchor strand having a sequence at least partially complementary to the at least one long and at least one short oligonucleotide. The invention also provides methods of synthesizing DNA molecules by assembling oligonucleotide members of a library that contains less than 20,000 members that can be assembled into all possible DNA sequences.

The invention provides methods of synthesizing a product DNA molecule having a desired and/or defined sequence. The methods involve assembling oligonucleotide members of a library that contains less than 20,000 members that can be assembled into all possible DNA sequences using the methods provided herein. Also disclosed are kits containing a library of 20,000 or less oligonucleotide members, where the oligonucleotide members in the library can be assembled into every possible polynucleotide sequence. Further disclosed are oligonucleotide libraries having less than 20,000 defined locations and having an oligonucleotide library member at each location, and the oligonucleotide library members can be assembled into every possible polynucleotide sequence.