The ATP Molecule

Note that the adenosine part of the ATP molecule has two parts: an adenine and the 5-carbon sugar ribose. Hence, another name for this molecule could be adenine ribose triphosphate. Adenosine triphosphate is the universal energy carrier molecule, and respiration can be considered an energy harvesting process.

In a simplified scheme, the phosphate group can be represented as , and the bond that links this group to the rest of the molecule can be shown as either __ , if a low-energy bond, or , if a high-energy bond. The ATP molecule, then, can be represented as shown in figure 10-3. ATP manufacture is a part of the respiration process in all organisms (figure 10-4).

Figure 10-3 A graphical way of representing ATP showing two high-energy bonds.

Figure 10-4 When a phosphate is added to adenosine diphosphate to make adenosine triphosphate, energy is invested. When a phosphate is broken away from ATP (thus returning it to a diphosphate), energy is liberated.