Definition of GRAVAMEN: The burden or gist of a charge; the grievance or injury specially complained of.In English ecclesiastical law. A grievance complained of by the clergy befo The Law Dictionary Featuring Black's Law Dictionary Free Online Legal Dictionary 2nd Ed.
Phosphate and sugar make up the sides of a DNA ladder.
To answer your question, the sides, or the backbone of the DNA is made up of alternating phosphate and deoxyribose residues. On the carbon labeled #1 on the deoxyribose sugar, you have the base added to it. These bases form the rungs of the DNA molecule. Adenine, Thymine, Cytosine and Guanine are the four possible bases. There are two different types of bases, purines and pyrimidines. They refer to the basic structure, or backbone if you will, of the bases.