3.11- ATP

Question 1

What are the main activities cells require energy for?

Answer 1

1. Synthesis- eg. large molecules like proteins.
2. Transport- eg. Pumping molecules/ ions across cell membranes by active transport.
3. Movement- eg. Muscle contraction.

Question 2

What is ATP (and structure)?

Answer 2

Inside cells, molecules of adenosine triphosphate supply energy.
- composed of a nitrogenous base, a pentose sugar and three phosphate groups.
-Base= adenine.
-Sugar= ribose.
Known as universal energy currency because it is used for energy transfer in all cells of all living things.

Question 3

How does ATP release energy?

Answer 3

• only a small amount of energy is needed to break the weak bond holding the last phosphate group. However, a large amount of energy is released later when the phosphate undergoes other reactions. Overall more energy is released than used.
  -hydrolysis reaction:
  ATP + H20 —> ADP + P1 + energy

Question 4

Is ATP a good long term store?

Answer 4

ATP isn’t a good long-term store due to the instability of the phosphate bonds.

• the energy released in the breakdown of fats/carbohydrates creates ATP by reattaching a phosphate group to an ADP molecule. This is called phosphorylation and is a condensation reaction.
• due to instability, cells do not store large amounts of it, however ATP can be rapidly reformed by the phosphorylation of ADP so is therefore a good immediate energy

Question 5

What are the properties of ATP?

Answer 5

• small: moves easily in/out of cells.
• water soluble: energy-requiring processes happens in aqueous environments.
• contains bonds between phosphates with intermediate energy: large enough to be useful for cellular reactions but not so large that energy is wasted as heat.
• releases energy in small quantities: suitable to cellular needs.
• easily regenerated: can be recharged with energy.