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

If you are unsure Of any of the key biological principles in respiration and photosynthesis there are some good links below http://mediadev.pearsoncmg.com/intl/snab_2009/skills_support/biochem/biochem_20/bc_t20.html (redox reactions) http://media.pearsoncmg.com/intl/snab_2009/skills_support/biochem/biochem_16/bc_t16.html (electron chains) http://media.pearsoncmg.com/intl/snab_2009/skills_support/biochem/biochem_18/bc_t18.html (co enzymes)

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!

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!

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!

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.

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

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

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

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