Synthetic DNA – Oligonucleotide Synthesis

As the name suggest, it is about synthesizing DNA molecule in the lab itself. Synthesis of artificial DNA does not require template as required in the living cell at the time of DNA synthesis.

So far, the manipulation of DNA purified from living cells has been reviewed. However, the ability to synthesize short pieces of DNA called oligonucleotides was another important advance.

Oligonucleotides are generally 15 to 30 nucleotides long, and can be either DNA or RNA.

DNA oligonucleotide are synthesized by a stepwise process in which single nucleotides are added to the end of the growing chain. The 3’ end of the chain is attached to a solid support such as a silica gel particle. A DNA synthesizer or “gene machine” carries out the solid-phase synthesis. A specially activated nucleotide derivative is added to the 5’ end of the chain is separated from the reaction mixture by filtration or centrifugal ion. The process is then repeated to attached another nucleotide. In a relatively short time, chains of 50 to 100 nucleotides long can be synthesized.

Oligonucleotide synthesis technique is of great importance in current laboratory practices. Because it provide a rapid and inexpensive access to customer made oligonucleotides of the desired sequence. Whereas if we seen the synthesis of DNA in cell by various enzymes, it is in 5’ to 3’ direction. But on the oligonucleotide synthesis in lab this limit is also overcomes.  So, we can also synthesize artificial DNA in the opposite direction (out side cell only) i.e. 3’ to 5’.

Oligonucleotide synthesized in laboratory are of great importance in molecular biology and medicine. They are most commonly used as antisense oligonucleotides. Small interfering RNA, primers for DNA sequencing and amplification. Probes for detecting complementary DNA or RNA via molecular hybridization, tools for the targeted introduction of mutations and restriction sites, and for the synthesis of artificial genes.

Reference: Prescott Microbiology, Wiki