The structure of nucleic acids. Type of connection between mononucleotides??

1 Answer
Mar 8, 2018

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Nucleotides have two kinds of connections that hold them together. The first is the glycosidic bond from the anomeric carbon on the Ribose sugar to the N atom on the base (GTACU). This is sometimes called an N-linked glycosidic bond.
The other connection is a phospho-ester bond from the 5` hydroxy group on the ribose sugar to a phosphate group. These connections make up the monomers of nucleotides.

All nucleotide monomers have 2 important reactive ends. The 5Phosphate and the 3 Hydroxyl group on the ribose sugar.

When 2 monomers for a dimer (dinucleotide), the 5Phosphate of one monomer forms a phosphoester bond with the 3 hydroxyl group of the other monomer. The phosphate group that is linking them contains 2 ester bonds - one to each monomer.

The linkage between the monomers in a dinucleotide is called a phospho-diester bond. Now your dinucleotide still has a free 3` hydroxyl group, so the next monomer can add onto this site and you'll get a trimer...and on and an oligonucleotide...polynucleotide, etc.