Question

Write an equation for the hydrolysis of ATP to ADP.

Short answer

ATP + H2O → ADP + Pi + Energy

Step-by-step solution

Identify the reactants

The reactants in the hydrolysis of ATP (adenosine triphosphate) are ATP and water (H2O).

Identify the products

The products in the hydrolysis of ATP are ADP (adenosine diphosphate), an inorganic phosphate (Pi), and energy.

Write the chemical equation

Combine the reactants and products into a balanced chemical equation: ATP + H2O → ADP + Pi + Energy

Key concepts

ATP

ATP, or Adenosine Triphosphate, is often called the 'energy currency' of the cell. It carries energy within cells for metabolism.
ATP consists of three components: the nitrogenous base adenine, the sugar ribose, and three phosphate groups. The bonds between these phosphate groups (especially the one between the second and third phosphate) are high-energy bonds.
When cells need energy, they break these high-energy bonds. The energy released is then used for various cellular processes, like muscle contractions, nerve impulse propagation, and chemical synthesis.

ADP

ADP stands for Adenosine Diphosphate. It is closely related to ATP but has only two phosphate groups instead of three.
When ATP undergoes hydrolysis, it loses one of its phosphate groups, transforming into ADP.
ADP can be reconverted into ATP by the addition of a phosphate group in a process known as phosphorylation. This occurs during cellular respiration or photosynthesis, where the energy from nutrients or sunlight drives this conversion, making more ATP available again.

Chemical Equation

A chemical equation represents a chemical reaction with symbols and formulae. In the case of ATP hydrolysis, the equation shows the transformation of ATP and water (H2O) into ADP, an inorganic phosphate (Pi), and energy.
The balanced chemical equation for the hydrolysis of ATP is:
ATP + H2O → ADP + Pi + Energy
Reactants (left side) are ATP and water, while the products (right side) are ADP, Pi, and energy.
This equation demonstrates how energy is released during the reaction, which the cell then uses to perform various functions.

Phosphate Group

Phosphate groups are important molecular components consisting of a phosphorus atom bound to four oxygen atoms. In ATP, there are three phosphate groups, labeled alpha, beta, and gamma.
The breaking of the bond between the beta and gamma phosphates (the outermost ones) during ATP hydrolysis releases a significant amount of energy.
This released phosphate (inorganic phosphate or Pi) then can be utilized in various biochemical reactions. The energy released when the bond is broken is used by cells to perform work.

Energy Release

The energy released during the hydrolysis of ATP is crucial for nearly all cellular functions.
When ATP is hydrolyzed to ADP and an inorganic phosphate, energy is released due to the breakdown of the high-energy bond. This energy is then available to the cell.
The cell uses this energy for processes like muscle contractions, protein synthesis, and cell division. Essentially, the energy extracted from ATP hydrolysis is the driving force behind many biological activities.