1. Learning Outcomes
Explain the importance of coenzymes in respiration, with reference to NAD and coenzyme A;
What is a coenzyme?
Molecules that help enzymes carry out oxidation or reduction reactions
Act like shuttles carrying atoms or molecules from one enzyme controlled reaction to another

2. If you are unsure
Of any of the key biological principles in respiration and photosynthesis there are some good links below
(redox reactions)
(electron chains)
(co enzymes)

3. Respiration Respiration of glucose can be summarised in four stages
Glycolysis
The link reaction
Krebs cycle
Oxidative Phosphorylation
Before going to next slide: summarise where each occur and the main events
Check!

4. Outline of respiration:
1.GLYCOLYSIS:
Cytoplasm of cells
Aerobic and anaerobic
6C glucose broken down to 2x3C Pyruvate
3.KREBS CYCLE
Matrix of mitochondria
Acetate is decarboxylated and dehydrogenated
2. LINK REACTION:
Matrix of mitochondria
Pyruvate is dehydrogenated and decarboxylated : acetate
4. OXIDATIVE PHOSPHORYLATION
Inner membranes of mitochondria (cristae) ATP!

5. Coenzymes in Respiration
During respiration, hydrogen atoms are removed from substrate molecules in oxidation reactions.
This is catalysed by dehydrogenase enzymes
Co enzymes are required to activate the oxidation reactions in respiration
Hydrogen atoms becomes attached to co enzymes e.g. NAD
These carry the hydrogen atoms to inner mitochondrial membrane where they are split into protons and electrons (oxidative phosphorylation)
Once delivered they are reoxidised and can pick up more hydrogen atoms!

6. NAD Nicotinamide adenine dinucleotide (NAD)
Helps dehydrogenase enzymes carry out their function.
Made of 2 linked nucleotides (di). One nucleotide has the base adenine, the other contains nicotinamide ring that can accept hydrogen atoms.
Is reduced when it has accepted two hydrogen atoms with their electrons
Operates in glycolysis, link reaction, the Krebs cycle and the anaerobic pathways.

7. Coenzyme A
Structure:
Adenosine (adenine+ ribose), 3 phosphate groups, panthenoic acid and a small cysteamine group
Function
To carry ethanoate (acetate) groups made in the link reaction, onto the Krebs cycle
To carry acetate groups made from fatty acids or amino acids onto the Krebs cycle

8. FAD Derived from vitamin B2
Made from Adenine Ribose and 2 phosphate groups
FAD  FADH
Used in the Krebs cycle

9. Question:
Explain why living organisms do not have very much NAD or CoA in their cells
Recycled/regenerated!

10. TASKS:
Review page 82-3
Make a list of the key words and their definitions
Summarise key points under learning outcome