Question

Discuss ATP synthesis and ATP hydrolysis; How do cells obtain the energy to synthesize

ATP? Why do cells hydrolyze ATP? What do cells do with released energy obtained from

the hydrolysis of ATP?

Answer 1

• ATP (adenosine triphosphate) synthesis refers to the reaction by which ATP molecule is produced from ADP (adenosine diphosphate).
• This involves addition of an inorganic phosphate group (Pi) to ADP molecule (phosphorylation). The enzyme involved is ATP synthase.
• The reaction for ATP synthesis can be shown as :

ADP + Pi + energy + ATP

• ATP hydrolysis on the other hand is the process by which ATP is broken down into ADP and Pi, along with the release of energy. The reaction can be shown as :

ATP + H2O + ADP + Pi + Energy

• Cells obtain energy for ATP synthesis from the proton (H+) gradient created during the electron transport chain.
• Cells hydrolyze ATP to release energy present in the chemical bonds of ATP.
• Cells perform metabolic, physical and maintenance functions using the energy released from ATP hyrolysis.

We can summarise the answer as :

ATP synthesis	ATP hydrolysis
It involves the reaction: ADP+Pi ---> ATP Requires input of energy, and occurs in the mitochondrial membrane. Energy for the reaction comes from proton gradient, created via electron transport chain.	It involves the reaction: ATP + H2O ---> ADP + Pi It releases energy (energy is evolved). Released energy is used to perform cellular functions, like metabolism and maintenance.