BIOCHEM FINAL - ATP Energy currency

Cells tightly regulate ATP, ADP, and Pi levels, maintaining a high phosphorylation

Why is ATP’s phosphorylation potential in cells higher than its standard free energy of hydrolysis?

In high-energy phosphate bonds (like in ATP) and thioester bonds

Where is chemical energy stored in living systems?

1. physical coupling by enzymes (bringing molecules together)

2. chemical coupling via phosphoryl transfer (ATP donating phosphate)

What two types of coupling do biological systems require to use ATP’s energy

They gain charge separation and resonance stabilization, which the reactants lack

Why do ATP hydrolysis products have lower energy?

It reduces the number of enzymes cells need and provides multiple energy levels for different reactions

Why is ATP the universal energy carrier?

Three—depending on whether ATP → ADP, ATP → AMP, or ADP → AMP.

How many energy levels can ATP provide?

Yes. their phosphoryl bond energies are functionally equivalent

Are phosphoryl bonds equivalent among all NTPs (ATP, GTP, CTP, UTP)?

it is equivalent to breaking two ATP molecules (2 ATP equivalents)

How much energy is released when ATP is hydrolyzed to AMP + 2 Pi?