Adenosine diphosphate

Adenosine diphosphate (ADP), also known as adenosine pyrophosphate (APP), is an important organic compound in metabolism and is essential to the flow of energy in living cells. ADP consists of an adenosine molecule and two phosphate groups. The bond between the phosphate groups can be broken by hydrolysis to form adenosine monophosphate (AMP) and release energy.

Structure

ADP is composed of three main structural components: an adenosine molecule, a ribose sugar, and two phosphate groups. The adenosine molecule is composed of an adenine base attached to a ribose sugar. The two phosphate groups are attached to the ribose sugar. The phosphate groups are the key to the ability of ADP to store and release energy.

Function

ADP is crucial in cellular respiration, specifically in the processes of glycolysis, the Krebs cycle, and oxidative phosphorylation. In these processes, energy stored in the bonds of glucose and other molecules is transferred to ADP, which then becomes adenosine triphosphate (ATP). ATP can then be used to power other cellular processes that require energy.

Role in Energy Transfer

ADP is often referred to as the energy currency of the cell. This is because it plays a vital role in the transfer of energy within the cell. When a cell needs to perform work, it breaks down ATP, releasing energy and forming ADP. When the cell has excess energy, it can add a phosphate group to ADP to form ATP, storing the energy for later use.

See Also

• Adenosine triphosphate
• Cellular respiration
• Metabolism
• Phosphorylation