Pentose Sugar

Complete hydrolysis of Nucleic acids yields :

1. Pentose Sugar.
2. Nucleotide (or a base pair).
3. And Phosphoric acid.

I already had written about them, check the links marked above.

Pentose Sugar : 

These sugars are the compound having a 5-C ring structure.

* In DNA molecule, the sugar moiety is B-D-2-Deoxyribose.

* In RNA molecule, the sugar moiety is B-D-Ribose. 

{ NOTE : Here B-Beta which is an annomeric form, while D means

                the location of a functional group (F gp.) i.e., -OH right

                and above the last C-atom and the number is the change

                in the F gp. at the 2nd C-atom. }

* Well the importance of Pentose sugar in a nucleotide is, that it provides

   site for the Base and the Phosphate group as shown below.

       Base                          Base                           Base

          |                                 |                                  |

----Sugar---Phosphate--(-Sugar---Phosphate-)_n--Sugar---
Well I designed it my own LOL !!!

So, Sugar+Phosphate is a kind of backbone to the nucleic acids or the polynucleotide chain.

Polynucleotide chain or DNA