Dideoxynucleotides (abbreviated as ddNTP) are nucleotides lacking a 3'-hydroxyl group (-OH) in deoxyribose.
The lack of this hydroxyl group implies the inability to form a phosphodiester bond with other nucleotides, which occurs between the 5'-phosphate group of one and the 3'-hydroxyl group of another. Thus, during the replication of a DNA molecule, the addition of a ddNTP to the new synthesis chain assumes that the process stops. This is useful in DNA sequencing processes, as in the Sanger method.
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