ATP Cycle

Introduction to ATP and ADP

• ADP (Adenosine Diphosphate)
  • Consists of adenosine and two phosphate groups.
• ATP (Adenosine Triphosphate)
  • Consists of adenosine and three phosphate groups.

Conversion of ADP to ATP

• Process: Addition of an inorganic phosphate to ADP.
• Energy Requirement:
  • Energy input is required to convert ADP to ATP.
  • This is an endergonic reaction (energy absorbed).

Conversion of ATP to ADP

• Process: Removal of a phosphate group from ATP.
• Energy Release:
  • Energy is released during the conversion.
  • This is an exergonic reaction (energy released).
• Role of Water:
  • Water is required to break a phosphate bond.
  • This is a hydrolysis reaction.

Summary of Reactions

• ATP + Water → ADP + Phosphate + Energy
  • Example of hydrolysis.
  • An exergonic reaction since energy is released.
• ADP + Inorganic Phosphate + Energy → ATP + Water
  • Example of dehydration synthesis (forming a bond and releasing water).
  • An endergonic reaction as energy is put into the system.

Importance of ATP

• Short-term Energy Storage:
  • ATP serves as a form of short-term energy storage within cells.
• Energy Utilization:
  • When ATP is converted back to ADP, the released energy is used for:
    • Powering active transport.
    • Synthesizing molecules.
    • Driving other endergonic reactions.
• ATP as Energy Currency:
  • ATP is vital for cellular processes and is often referred to as the "energy currency" of the cell.