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 DdNTP refers to Dideoxynucleotides triphosphates which are used in Sanger dideoxy method to produce different lengths of DNA strands for DNA sequencing. DdNTP includes ddATP, ddTTP, ddCTP and ddGTP. DdNTP are useful in the analysis of DNA's structure as it stops the polymerisation of a DNA strand during a DNA replication, producing different lengths of DNA strands replicated from a template strand. These newly synthesised DNA strands are used later in gel-electrophoresis to generate a series of bands pattern which are useful to analyse the sequence of the DNA strand.

DdNTP differs from dNTP by the lack of 3'-OH group on the pentose sugar structure. A hydrogen group was found on the position 3' instead of OH-group. This results in the termination of DNA polymerisation(or DNA elongation) process because this process needs a 3'-OH group to continue.

DdNTP are often dyed(labelled with a certain fluorescent) to ease the analysis of the DNA sequence. Dyed DdNTP will fluoresces at different wavelengths which can be detected by modern technologies. A diagram of different wavelength analysed will be generated with base labelled.[1]


  1. Berg J, Tymoczko J, Stryer L, 2012 Biochemistry, 7th edition, New York, W. H. Freeman and Company. Pg. 149.
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