A sugar-phosphate backbone (alternating grey-dark grey) joins together nucleotides in a DNA sequence. The sugar-phosphate backbone forms the structural framework of nucleic acids, including DNA and RNA. This backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.
Herein, why are phosphate bonds easy to break?
These bonds are in fact relatively weak. They do involve high energy electrons but the bonds themselves are quite easy to break. The high negative charge density associated with the three adjacent phosphate units of ATP also destabilizes the molecule, making it higher in energy.
How many high energy phosphate bonds does ADP have?
The bond between two phosphate groups is a phosphoanhydride bond. This bond is less stable and is considered a high-energy bond. Adenosine diphosphate (ADP) can provide more energy than AMP. In ATP there are three phosphate groups with two high-energy bonds as shown in the image below.