1.6 ATP

Question 1

Describe the structure of ATP

Answer 1

• Stands for Adenosine Triphosphate.
• Consists of: a ribose sugar, the nitrogenous base adenine and 3 phosphate groups.

Question 2

How does ATP release energy

Answer 2

• Energy is released when ATP is hydrolysed to form ADP (adenosine diphosphate) and an inorganic phosphate molecule.
• ATP + H2O => ADP + Pi
• The energy comes from the bonds between the phosphate molecules.
• The 3rd phosphate bond is very unstable, so has a low activation energy - it can be broken easily and quickly.

Question 3

How can the inorganic phosphate formed be used

Answer 3

It can be used to phosphorylate other compounds, making them more reactive.

Question 4

How is ADP + Pi turned back into ATP and what kind of reaction is this

Answer 4

The condensation of ADP and inorganic phosphate, catalysed by ATP synthase produces ATP during photosynthesis and respiration.

Question 5

What are 3 key properties of ATP

Answer 5

• It is an immediate energy source and is more desirable to use than glucose as ATP can be broken down in a single step to release a manageable amount of energy (less energy is wasted).
• ATP isn’t stored in large quantities as it can easily be reformed from ADP in seconds (can release energy quicly and easily).
• ATP can be used in a variety of different ways (versatile source of energy), such as: metabolic processes, movement, active transport, secretion and activation of molecules.