Sanger sequencing
In Sanger sequencing, dideoxynucleotides stop DNA synthesis because they lack:
Answer B: explanation for every choice
A
Dideoxynucleotides have 5′-triphosphates, which let them be incorporated.
B
Correct. Without a 3′-OH, the next nucleotide cannot be attached by a phosphodiester bond.
C
They have a base, which is how each termination identifies a position.
D
Normal DNA nucleotides already lack a 2′-OH. The dideoxy form lacks the 3′-OH as well.
TakeawayNo 3′-OH → chain terminates.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb131.