How Is ATP Formed?

Adenosine triphosphate, or ATP, is formed via photosynthesis and cellular respiration. ATP is the high-energy carrying molecule that drives vital biological functions for an organism to survive.

ATP is utilized by the cells in a variety of ways. It is mainly used in most animals for muscular contraction, protein synthesis and cognitive processes. Photosynthetic organisms, however, use ATP as a raw material to produce essential bio-molecules, such as glucose and oxygen.


Organisms that are capable of photosynthesis, including green plants and other autotrophs, create ATP from carbon dioxide, water and captured sunlight energy. This process involves two stages: light reactions and dark reactions. During the light reactions, the energy from the sun is converted into chemical energy in the form of ATP. Adenosine diphosphate, or ADP, undergoes photophosphorylation, where a phosphate group is added to it to form ATP molecules. Another product of the light reactions is NADPH. During the dark reactions, also referred to as the “Calvin cycle,” the ATP and NADPH molecules are broken down to provide the energy required for the synthesis of glucose.

Cellular respiration

Animals rely on cellular respiration to produce usable energy. This set of metabolic pathways is driven by glucose, the primary organic product of photosynthesis. These pathways include glycolysis and aerobic respiration, further broken down into two: citric acid cycle and electron transport chain. Through a series of biochemical reactions coupled with enzymatic actions, glucose becomes completely oxidized at the end of cellular respiration to form 36 molecules of ATP.