Summary
The cell's energy currency, whose phosphate bond hydrolysis powers work in the cell.
In depth
The ATP/ADP cycle turns over rapidly: an average adult makes and uses around 50 kg of ATP a day. ATP is regenerated by substrate-level phosphorylation and oxidative phosphorylation. The energy is released by hydrolysis of terminal phosphate (about -30.5 kJ/mol standard).
ATP is rapidly recycled; cells hold only a few seconds' supply. High-energy phosphate transfer is reversible. Other nucleotides such as GTP serve specific roles.
Common mistake: ATP is not stored in large amounts; fat and glycogen are the stores.
Adenosine triphosphate has an adenine base, a ribose sugar and three phosphate groups. The bonds between the phosphates are high-energy because the negative charges repel and products are stabilised; hydrolysis to ADP and inorganic phosphate releases about 30.5 kJ per mole under standard conditions, and more in cells.
ATP couples energy-releasing reactions to work such as muscle contraction, active transport and biosynthesis, often by phosphorylating a protein. A person turns over roughly their own body weight in ATP each day; cells hold only a few seconds' supply and regenerate it continuously by respiration.
Example: the sodium-potassium pump uses about a third of a resting cell's ATP.
Remember: ATP is a short-term energy currency, not a long-term store.
Frequently asked questions
What is ATP?
The cell's energy currency, whose phosphate bond hydrolysis powers work in the cell.
Which area of biology covers ATP, and how advanced is it?
ATP is one of the 53 topics in Metabolism & Bioenergetics. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Anabolism and Catabolism, NAD and FAD, Cellular Respiration.
Can you give an example of ATP?
ATP is used by the sodium-potassium pump and in muscle contraction.
What should I learn before ATP?
ATP is a Beginner topic, so no earlier topic is required. Other Beginner topics in Metabolism & Bioenergetics that pair well with it include Metabolism, Anabolism and Catabolism, Cellular Respiration.
What topics are related to ATP?
The closest topics to ATP are Anabolism and Catabolism, NAD and FAD, Cellular Respiration, Metabolism. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand ATP?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for ATP. To practise the whole of Metabolism & Bioenergetics, use the Metabolism & Bioenergetics quiz.
How is ATP different from Anabolism and Catabolism?
ATP: The cell's energy currency, whose phosphate bond hydrolysis powers work in the cell. Anabolism and Catabolism: Anabolic reactions build complex molecules using energy; catabolic reactions break them down to release energy. Read both side by side and note what each one explains.
What is a common mistake about ATP?
ATP is not stored in large amounts; fat and glycogen are the stores.
How should I study ATP step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Anabolism and Catabolism and explain the difference aloud. Finally, take the Metabolism & Bioenergetics quiz and come back to this page for any question you miss.