How can atp store energy

ATP collects small packets of energy from the food-burning power plants of the cell and transports this energy to where it is needed. Some energy in ATP is released to do work, such as move muscles or force a seedling out of the ground. At other times, ATP gives up its energy to a nonspontaneous synthetic reaction, such as the formation of sucrose.

ATP is used to close the energy gap between energy-releasing reactions food breakdown and energy-requiring reactions synthesis. When a molecule of fatty acid is burned, energy is given off. Some of this energy is trapped in molecules of ATP, and some is lost in the form of heat. Each ATP molecule can then be transported elsewhere within the cell and used where needed. The energy-carrying part of an ATP molecule is the triphosphate "tail".

At the heart of ATP is a molecule of adenosine monophosphate AMP , which is composed of an adenine molecule bonded to a ribose molecule and to a single phosphate group Figure 1. The addition of a second phosphate group to this core molecule results in the formation of adenosine diphosphate ADP ; the addition of a third phosphate group forms adenosine triphosphate ATP.

The addition of a phosphate group to a molecule requires energy. Phosphate groups are negatively charged and thus repel one another when they are arranged in series, as they are in ADP and ATP.

The release of one or two phosphate groups from ATP, a process called dephosphorylation , releases energy. Hydrolysis is the process of breaking complex macromolecules apart. Water, which was broken down into its hydrogen atom and hydroxyl group during ATP hydrolysis, is regenerated when a third phosphate is added to the ADP molecule, reforming ATP. Obviously, energy must be infused into the system to regenerate ATP.

Where does this energy come from? In nearly every living thing on earth, the energy comes from the metabolism of glucose. In this way, ATP is a direct link between the limited set of exergonic pathways of glucose catabolism and the multitude of endergonic pathways that power living cells. Recall that, in some chemical reactions, enzymes may bind to several substrates that react with each other on the enzyme, forming an intermediate complex.

An intermediate complex is a temporary structure, and it allows one of the substrates such as ATP and reactants to more readily react with each other; in reactions involving ATP, ATP is one of the substrates and ADP is a product. During an endergonic chemical reaction, ATP forms an intermediate complex with the substrate and enzyme in the reaction.

This intermediate complex allows the ATP to transfer its third phosphate group, with its energy, to the substrate, a process called phosphorylation. This is illustrated by the following generic reaction:. When the intermediate complex breaks apart, the energy is used to modify the substrate and convert it into a product of the reaction. The ADP molecule and a free phosphate ion are released into the medium and are available for recycling through cell metabolism.

Figure 2. In phosphorylation reactions, the gamma phosphate of ATP is attached to a protein. ATP is generated through two mechanisms during the breakdown of glucose. A few ATP molecules are generated that is, regenerated from ADP as a direct result of the chemical reactions that occur in the catabolic pathways. A phosphate group is removed from an intermediate reactant in the pathway, and the free energy of the reaction is used to add the third phosphate to an available ADP molecule, producing ATP Figure 2.

In a process called cellular respiration, chemical energy in food is converted into chemical energy that the cell can use, and stores it in molecules of ATP. This occurs when a molecule of adenosine diphosphate ADP uses the energy released during cellular respiration to bond with a third phosphate group, becoming a molecule of ATP.

So the energy from cellular respiration is stored in the bond between the 2nd and 3rd phosphate groups of ATP. When the cell needs energy to do work, ATP loses its 3rd phosphate group, releasing energy stored in the bond that the cell can use to do work. Now its back to being ADP and is ready to store the energy from respiration by bonding with a 3rd phosphate group. How does atp store and release energy?