Respiration To be able to explain The biochemistry of aerobic respiration to show that glycolysis involves the oxidation of glucose to pyruvateThe biochemistry of aerobic respiration to show that glycolysis involves the oxidation of glucose to pyruvate That pyruvate combines with coenzyme A to produce acetylcoenzyme AThat pyruvate combines with coenzyme A to produce acetylcoenzyme A

Aerobic Respiration Define the following: Respiration Breathing Aerobic respiration Anaerobic respiration

Aerobic Respiration Respiration is the process that releases energy in organic molecules such as sugars and lipids. Respiration takes place in all cells all of the time Breathing is the mechanical process that supplies oxygen to the body for respiration and that removes carbon dioxide produced. Breathing ventilates the gas exchange surfaces. Aerobic Respiration is respiration with oxygen – most organisms respire aerobically releasing a relatively large amount of energy. Anaerobic respiration is respiration without oxygen – some organisms mainly bacteria can only respire anaerobically others can switch to anaerobic when oxygen levels are low.

Aerobic respiration describes the cell processes that require oxygen to release energy from all organic molecules. Respiration involves the breakdown of many molecules from the food we eat. Humans respire mainly sugars but also some amino acids and fatty acids. Aerobic Respiration

For any chemical reaction to occur energy is required to break bonds. The process of forming new bond can either require energy or release energy For there to be a release of energy the products of respiration must be at a lower energy level than the reactants.

Aerobic Respiration Energy in molecules Time Glucose and oxygen CO 2 +H 2 O

Aerobic Respiration What is the basic equation for respiration? C 6 H 12 O 6 + 6O 2  6CO 2 + 6H ENERGY In reality cell respiration takes place in a series of stages, these can produce a up to 36 molecules of ATP per molecule of glucose The steps involved in respiration rely on a series of redox reactions C 6 H 12 O 6 + 6O 2  6CO 2 + 6H ATP

Aerobic Respiration The process of aerobic respiration can be divided into 4 distinct processes: Glycolysis Pyruvate Oxidation The Krebs cycle The electron transport chain

Mitochondria What are mitochondria? Mitochondria are membrane-enclosed organelles distributed through the cytosol of most eukaryotic cells. Their main function is the conversion of the potential energy of food molecules into ATP. Mitochondria have: an outer membrane that encloses the entire structure an inner membrane that encloses a fluid-filled matrix between the two is the intermembrane space the inner membrane is elaborately folded with shelflike cristae projecting into the matrix. a small number (some 5–10) circular molecules of DNA

Mitochondria

StageSite Within CellOverall processNumber of ATP molecules produced Aerobic Respiration Use the information on pages 11 and 12 to complete the table

Aerobic RespirationStage Site Within Cell Overall process Number of ATP molecules produced GlycolysisCytosol Glucose is split into 2 molecules of pyruvate 2 per glucose molecule Pyruvate Oxidation Matrix – inner fluid of mitochondria Pyruvate is converted to acetyl co A none Krebs Cycle Acetyl co A drives a cycle of reactions to produce hydrogen 2 per turn so 4 per glucose Electron Transport Chain Inner membrane of mitochondria Hydrogen drives a series of redox reactions to produce ATP Up to 32 per glucose

Four stages of aerobic respiration GlycolysisGlycolysis The link reactionThe link reaction Krebs cycleKrebs cycle Electron transport chainElectron transport chain

Glossary the addition of phosphate groups to a molecule.the addition of phosphate groups to a molecule. the ‘splitting’ of glucose.the ‘splitting’ of glucose. nicotinamide adenine dinucleotidenicotinamide adenine dinucleotide coenzyme Acoenzyme A acetylcoenzyme Aacetylcoenzyme A tricarboxylic acidtricarboxylic acid flavin adenine dinucleotideflavin adenine dinucleotide Phosphorylation Glycolysis NAD coA acetyl coA TCA FAD

Glycolysis Glycolysis is a series of biochemical reactions by which a molecule of glucose is oxidised to two molecules of pyruvic acid. Glycolysis serves two principal functions: generation of high-energy molecules (ATP and NADH), and production of a variety of six- or three-carbon intermediate metabolites. Glycolysis is one of the most universal metabolic processes known, and occurs (with variations) in many types of cells in nearly all types of organisms.

Glycolysisglucose phosphorylation 2ATP 2P 2ADP Glucose phosphate (6C)

Glycolysisglucose phosphorylation 2ATP 2P 2ADP (6C) triose phosphate (3C) glycerate-3- phosphate

Glycolysisglucosephosphorylation 2ATP 2P 2ADP Glucose phosphate triose phosphate glycerate-3-phosphateglycerate-3-phosphate 2ADP + 2Pi 2ATP 2ATP 2NAD + HH 2NADH + H + pyruvatepyruvate

2 triose phosphate 2 glycerate-3-phosphate 2ADP + 2Pi 2ATP 2NAD + H 2NADH + H + 2 pyruvate The triose phosphate is oxidised (loses an electron)The triose phosphate is oxidised (loses an electron) Coenzyme NAD + collects hydrogen ions forming 2 reduced NAD (NADH +H + )Coenzyme NAD + collects hydrogen ions forming 2 reduced NAD (NADH +H + ) 4 ATP are produced, but 2 were used up at the beginning, therefore there is net gain of 2 ATP4 ATP are produced, but 2 were used up at the beginning, therefore there is net gain of 2 ATP

Glycolysis in cytoplasm Glucose 2 ATP 2 NADH 2 Pyruvate 4 ATP Overview of Glycolysis 2 NADH 2 Pyruvate To mitochondria ATP For use in the cell for work

The Link reaction Literally ‘links’ glycolysis to the Krebs cycleLiterally ‘links’ glycolysis to the Krebs cycle Sometimes treated as part of the Krebs cycleSometimes treated as part of the Krebs cycle Pyruvate enters the matrix of the mitochondriaPyruvate enters the matrix of the mitochondria

Link Reaction Pyruvate (3C) 2NAD + H 2NADH + H + The pyruvate is dehydrogenated (hydrogen is removed) and the hydrogen is transferred to the hydrogen acceptor NAD + to form NADH + H + CO 2 The pyruvate is decarboxylated (a molecule of carbon is removed)

Link Reaction Pyruvate (3C) 2NAD + H 2NADH + H + CO 2 acetate (2C) + coenzyme A (CoA) acetyl coenzyme A (acetyl CoA) NO ATP is produced As 2 pyruvate molecules are formed from glucose there will be 2 molecules of acetyl CoA

The Link reaction pyruvate + CoA + NAD +  Acetyl CoA + CO 2 + NADH + H + Acetyl coenzyme A now enters the Krebs cycle

The Link Reaction

Make notes on mitochondria, glycolysis and the link reaction on pages 11 – 13Make notes on mitochondria, glycolysis and the link reaction on pages 11 – 13 Break it down into chunks and make sure you can remember how it starts and what the products areBreak it down into chunks and make sure you can remember how it starts and what the products are

1.Describe how oxidation takes place in glycolysis 2.What do the terms glycolysis and phosphorylation mean? 3.Why is there only a net gain of 2ATP during glycolysis? 4.How many molecules of ATP are produced in the link reaction? 5.Where is acetyl coenzyme formed?

1.Describe how oxidation takes place in glycolysis removal of hydrogen/dehydrogenation;removal of hydrogen/dehydrogenation; by enzymes/dehydrogenases;by enzymes/dehydrogenases; H accepted by NAD/reduced NAD formed;H accepted by NAD/reduced NAD formed; 2.What do the terms glycolysis and phosphorylation mean? glycolysis – splitting of glucoseglycolysis – splitting of glucose Phosphorylation - addition of phosphatePhosphorylation - addition of phosphate 3.Why is there only a net gain of 2ATP during glycolysis? 4 produced but 2 used at beginning so net gain of 24 produced but 2 used at beginning so net gain of 2 4.How many molecules of ATP are produced in the link reaction? nonenone 5.Where is acetyl coenzyme formed? Matrix of the mitochondriaMatrix of the mitochondria