1. ATP use, synthesis and structure
Outline why plants, animals and microorganisms need to respire, with reference to active transport and metabolic reactions;
Describe, with the aid of diagrams, the structure of ATP;
State that ATP provides the immediate source of energy for biological processes.

2. Uses for ATP
Adenosine triphosphate is the body’s most common energy source. It is used in every cell in the body for activities such as:
Active transport
Maintaining body temperature
Anabolic reactions (synthesis of smaller molecules into larger ones)
Catabolic reactions (degradation reactions)

3. The Structure of ATP
The structure of ATP is similar to that of a nucleotide. What two features are similar?
ATP is water soluble and so is easily transported across membranes within a cell.
Free electrons surround the phophate groups – these give the molecule its high energetic potential.
Nitrogenous base
3 phosphate groups
Adenine
5-carbon Ribose sugar

4. The Structure of ATP Adenosine Adenosine monophosphate (AMP)
Adenosine diphosphate (ADP)
Adenosine triphosphate (ATP)

5. ATP as a source of energy
The phosphate “tail” of an ATP molecule is where the main source of energy is.
Removal of a phosphate group by the process of hydrolysis (the addition of water) releases energy.
When ATP is hydrolysed to ADP, 30.5KJ of energy is released.
ADP can be further broken down into AMP, which also releases a small amount of energy.
Pi + ADP

6. ATP as a source of energy
The energy released as a result of hydrolysis can be channelled into other molecules and used directly by cells. Some energy is lost as heat.
ATP is continually being brown down and reformed at a rate of 8000 cycles per day.
30.5KJ released

7. How is ATP synthesised?
All living organisms use and synthesis ATP in different ways:
Plants - photophosphorylation
Yeast - glycolysis and fermentation
Animals – glycolysis and respiration
Varying amounts of ATP are produced in different reactions, as are the locations and requirements for oxygen.
Plant and animal ATP synthesis both require the enzyme ATP snythase (ATPase).

8. Where does the energy come from?
Photoautotrophs carry out photosynthesis to make large, complex molecules that contain chemical potential energy.
This energy is used by these organisms, as well as consumers and decomposers.
Respiration releases this energy, which is used to phosphorylate ADP to make ATP.

9. What does this diagram tell you
What does this diagram tell you? Explain it to a partner in your own words.

10. The Stages of Respiration
Glycolysis
The link reaction
Krebs cycle
Oxidative phosphorylation

11. Stage Location Products of this stage
Glycolysis
Cystol (cytoplasm)
Pyruvate
The link reaction
Matrix of Mitochondria
Acetate
Krebs cycle
Decarboxylated and dehydrogenated acetate
Oxidative phosphorylation
Cristae of mitochondria
ATP

13. The role of enzymes and coenzymes in respiration
Respiration is an enzyme-controlled process. It relies on different enzymes and coenzymes.
Dehydrogenase enzymes remove hydrogen from other molecules and make this hydrogen available to be passed on to coenzymes (this is important later).
Decarboxylase enzymes hydrolyse the carboxyl group (COOH) from a molecule, usually producing CO2
FAD and NAD are coenzymes that act as hydrogen acceptors for the dehydrogenase enzymes. They are needed as enzymes are not as efficient at reduction reactions.

14. NAD
A non-protein molecule that helps dehydrogenase enzymes to carry out oxidation reactions
NAD accepts two hydrogen atoms, along with their electrons. In this state, we say that NAD is reduced.
When it loses electrions, it is oxidised.

15. Structure of NAD (nicotineamide adenine dinucleotide)
Made of two linked nucleotides
Nicotinamide ring can accept hydrogen atoms.
These can split into hydrogen ions and electrons (later stage)