The primary structure of both DNA and RNA consists
of a polymeric chain of nucleotides. The formation of the polymeric
nucleotides follows the polyester synthesis principle. The nucleotides
are joined together by phosphate-ester bonds between the -OH
on carbon #3 of one pentose and the -OH on carbon #5 of the next
pentose which is referred to as the 3'-5' phosphate linkage.
An example of a partial primary structure for a fragment of RNA
is shown in the graphic on the left.
The backbone structure for either DNA or RNA is the
alternating pentose sugar and phosphate units. The heterocyclic
amines or bases which are part of this polymeric structure are
said to be "side chains" off of the "backbone"
The backbone for RNA as shown is alternating phosphate
- ribose - phosphate - ribose - etc. The possible bases
are adenine, cytosine, guanine, and uracil
DNA Single Strand - Chime
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|Quiz: For DNA, what is different
in the backbone?
|If you were to write out a similar
structure for all four nucleotides in DNA, what would be different?