Practice question

Sequencing-by-synthesis is the core principle of Illumina next-generation sequencing. Library fragments immobilized on flow cell are amplified into clusters, then polymerase synthesizes complementary strand stepwise. Each cycle adds fluorescently labeled reversible terminator dNTPs that block further extension until imaging is complete. After color detection identifying base, terminator and fluorophore are chemically cleaved to allow next incorporation. This iterative labeled nucleotide addition contrasts with ligation-based SOLID, hybridization microarrays relying on probe annealing, or pH change detection in Ion Torrent. Hence labeled nucleotide addition defines SBS.