ATP (Adenosine Triphosphate) is referred to as the universal energy currency and is used in three main type of activity:
- Synthesis – Protein, lipid, carbohydrate, etc synthesis
- Transport – active transport, bulk transport, vesicles in cells
- Movement – contraction of muscle fibres, movement of cells
ATP is a nucleotide similar to RNA Adenine but has 3 phosphate heads instead of 1. When hydrolysed it releases it’s chemical potential in the form chemical energy (the release of its phosphate head). This will then attach to a specific site where it will cause conformational change and release energy.
Energy is needed to break bonds, but is released when new bonds are formed. The bonds between the phosphate heads are relatively weak and can be broken with a small amount of energy. However, when the released phosphate group undergoes other reactions, it released more energy (approximately 30.6kJ/mol)
The hydrolysis of ATP doesn’t happen in isolation, but occurs in association with energy-requiring reactions and they occur simultaneously.
The instability of ATP means that it is not a good long-term energy store, other biological molecules like fats and carbohydrates are better suited. The energy released from the breakdown of these stores generates energy that creates ATP. This occurs by using the energy to reattach the phosphate group to ADP (Adenosine Diphosphate) in a process called phophorylation which is a type of condensation reaction.
ATP has many properties which make it ideal for quick-energy usage:
- Small – allows it to move easily into, out of, or within cells.
- Water soluble – energy-requiring processes occur in aqueous environments.
- It contains bonds between phosphates with intermediate energy; large enough to be useful for cellular reactions but not so large that it is wasted as heat.
- Releases energy in small quantities.
- Easily regenerated – Can be recharged with energy
A-Level Revision 