ATP Cycle

ATP cycle (from video)

Core concepts

• ATP (adenosine triphosphate) contains three phosphate groups; ADP (adenosine diphosphate) contains two.
• Forming ATP from ADP + inorganic phosphate (Pi) requires an input of energy (endergonic) and releases water (dehydration synthesis). This makes ATP a short-term energy storage molecule.
• Breaking ATP into ADP + Pi releases energy (exergonic) and requires water (hydrolysis) to cleave the terminal phosphate bond.
• The cycle is reversible: energy is stored when ATP is formed and released when ATP is hydrolyzed back to ADP.
• ATP functions as the cell’s energy currency, powering processes such as active transport, biosynthesis, and other endergonic reactions.

Reaction summary

ATP + H2O → ADP + Pi + energy (hydrolysis — exergonic)

ADP + Pi + energy → ATP + H2O (dehydration synthesis / phosphorylation — endergonic)

• Hydrolysis of ATP releases energy that can be used immediately by the cell.
• Phosphorylation (reforming ATP) requires an energy source (e.g., cellular respiration, photosynthesis).

Applications / roles

• Short-term energy storage molecule.
• Provides energy for:
  • Active transport across membranes.
  • Synthesizing molecules (biosynthesis).
  • Driving other energy-requiring cellular reactions.

Researchers / sources

• No researchers or specific sources were mentioned in the video transcription.