ATP

Why do cells require enregy?

1. Synthesis

2. Transport

3. Movement

In cells, what molecules provide energy?

ATP

How does ATP release energy?

• A small amount of energy is needed to break the relatively weak bond holding the last phosphate group in ATP

• Large amounts of energy is released when free phosphate undergoes other reactions involving bond formation

• Water is involved in the removal of a phosphate group

  • Makes this a hydrolysis reaction

  • Happens in association w. energy-requiring reactions

What is ATP hydrolysed into?

ADP & an inorganic phosphate ion, which releases energy

Why is ATP not a good long-term energy store?

Due to the instability of the phosphate bonds in ATP

• Fats & carbs are better

What is the energy released from the breakdown of fats and carbs used for?

ATP production

Phosphorylation

Reattaching a phosphate group to a ADP molecule, making ATP

• Water is removed in this process

What is phosphorylation an example of?

A condensation reaction

Why is ATP a good immediate energy store?

• ATP is constantly being reformed rapidly by the phosphorylation of ADP

• As the interconversion of ATP &ADP is happening constantly in living cells, cells do not need a large store of ATP

Properties & Features of ATP (5)

• Small

  • Moves easily into, out of & within cells

• Water soluble

  • Energy-requiring processes happen in aqueous environments

• Contains bonds between phosphates w. intermediate energy

  • Large enough to be useful for cellular reactions but not so large that energy is wasted as heat

• Releases energy is small quantities

  • Quantities are suitable to most cellular needs, so energy isn’t wasted

• Easily regenerated