2.1.3 Nucleotides and Nucleic acids - ATP

Question 1

What is energy?

Answer 1

Energy is the ability to do work.

Question 2

Why do we need energy?

Answer 2

• Metabolism
• Movement
• Active transport
• Maintenance, repair, and division of cells
• Production of substances
• Maintenance of body temperature

Question 3

Where does energy come from?

Answer 3

Light energy is converted by plants into chemical energy during photosynthesis. The chemical energy from photosynthesis, in the form of organic molecules, is converted into ATP during respiration. ATP is used by cells to perform useful work.

Question 4

What does ATP stand for?

Answer 4

ATP stands for adenosine triphosphate

Question 5

What is ATP composed of?

Answer 5

An ATP molecule is composed of a nitrogenous base, a pentose sugar and three phosphate groups – it is a nucleotide.

Question 6

How does ATP release energy?

Answer 6

ATP can be hydrolysed to break a bond (between the last phosphate group in ATP) which releases a large amount of energy. (another example of a hydrolysis reaction).
A lot more energy is released than used, approximately 30.6 KJ mol-1.

Question 7

What enzyme catalyses the reaction?

Answer 7

Hydrolysis of ATP to ADP (adenosine diphosphate) is catalysed by the enzyme ATPase.

Question 8

What is the ATP reaction formula?

Answer 8

ATP + H2O –> ADP + Pi + energy

Adenosine triphosphate +| water –> adenosine diphosphate + inorganic phosphate + energy

Question 9

How can ADP + Pi reform/go back to ATP?

Answer 9

A phosphorylation reaction (another example of a condensation reaction).

Question 10

What are the properties of ATP?

Answer 10

• Small – moves easily into, out of and within cells
• Water soluble – energy-requiring processes happen 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 – quantities are suitable to most cellular needs, so that energy is not wasted as heat.
• Easily regenerated – can be recharged with energy.

Question 11

What are the advantages of ATP?

Answer 11

• Instant source of energy
• Releases energy in small amounts as needed
• It is mobile and transports chemical energy to where it is needed IN the cell
• Universal energy carrier and can be used in many different chemical reactions.