2. Nucleosides and nucleotides
A nucleoside is formed by the association of the
nitrogen containing base (A,T,C or G) with the pentose.
For purine bases, the bond is between atom 9 of the base and the carbon 1' of the pentose
(see below).
For pyrimidine bases, the bond is between atom 1 of the base and the carbon 1' of
the pentose (see below).
Nucleosides are created by reaction with phosphoric acid with the alcohol group in 5' of the sugar (esterification). below are the structures of the 4 nucleotides of DNA.
| Deoxyadenosine 5' monophosphate | Deoxythymidyine 5' monophosphate |
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| Deoxycytidine 5' monophosphate | Deoxyguanosine 5' monophosphate |
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 3.
Primary structure |
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