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Frequently asked questions

Our Scientific Applications Support team has assembled a list of frequently asked questions to help you find answers quickly. Filter using one or more categories to focus on specific topics, or use the search bar to perform a text search.

How can I assemble long, single-stranded oligos to create several kb, clonable gene sequences (assembly PCR)?

Assembly PCR is a very flexible technique for producing novel gene sequences from single-stranded oligos or a mix of single- and double-stranded DNA. Several single-stranded oligonucleotides, such as the IDT 60–120 nt Ultramer® Oligonucle­otides, can be designed with short overlap­ping sequences and then assembled in a 2-step process to produce longer genes of up to several thousand base pairs.

Con­siderations for setting up such reactions and a brief protocol can be found in the article, Assembly PCR for Novel Gene Synthe­sis, in DECODED 2.4, October 2012 (

IDT also offers gBlocks® Gene Fragments, custom synthe­sized, double-stranded DNA fragments that can streamline the assembly and cloning process. Learn more at

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