ATP: Energy Currency of the Cell - 3.2

Q: What does ATP stand for?

A: Adenosine triphosphate.

Q: Why is ATP important?

A: Many chemical reactions require the use of ATP.

Q: What processes does ATP aid in?

• Breaking chemical bonds

• Forming chemical bonds

• Cell/protein/molecule transfer

• Mechanical work (e.g., flagella movement)

Q: Why does ATP contain large amounts of free energy?

A: Because it has three negatively charged phosphate groups that crowd together.

Q: What happens when phosphate groups are close together?

A: Their negative charges create a repulsive force.

Q: Why are the bonds between the phosphate groups weak?

A: The repulsive forces make them weak, so they can break easily.

Q: What type of reaction catalyzes ATP?

A: Hydrolysis reaction (exergonic reaction).

Q: What happens during ATP hydrolysis?

• The terminal phosphate group breaks off.

• Forms ADP and a phosphate.

• OH is added to the solo phosphate group and a H+ is released into the solution

Q: What is produced from ATP hydrolysis?

A: ADP and Phosphate

Q: What is phosphorylation?

A: The transfer of a phosphate group from ATP to another molecule.

Q: How does ATP fuel chemical reactions?

Through phosphorylation — transferring a phosphate to another molecule.

Q: Describe the process of energy coupling:

• The phosphate group detaches from ATP.

• It becomes free to bind to a new molecule.

• With an enzyme’s help, the phosphate attaches to the reactant.

• The new molecule gains energy to proceed with the reaction.

• This results in more free energy.

Q: Why must ATP always be regenerated?

Because it is continuously used in cells — this process is called the ATP Cycle.

Q: What type of reaction is ATP synthesis?

A: Endergonic reaction.

Q: What is the formula for ATP synthesis?

A: ADP + Pi → ATP

Q: Where does the energy for ATP synthesis come from?

A: From the breakdown of complex molecules like carbohydrates, lipids, and proteins.

Q: Why is ATP called the “universal energy currency” of the cell?

Because it:

Can be reassembled immediately.

Can undergo energy coupling.

Is available through many food sources.