1. RESPIRATION OCR A2 Biology F214

2. Energy and the role of ATP Cells need chemical energy for biological processes to occur. Energy is used in ACTIVE TRANSPORT, MOVEMENT, HOMEOSTASIS, ANABOLIC REACTIONS.

3. ATP ATP (adenosine triphosphate) is small and water soluble, easily transported. Nucleotide base adenine, combined with a ribose sugar and 3 phosphate groups. ATP is a phosphorylated nucleotide, a nucleotide with extra phosphate groups added. ATP is used to carry energy from energy- releasing reactions to energy-consuming reactions.

4. How ATP carries energy ATP is synthesised from adenosine diphosphate (ADP) and an inorganic phosphate group using the energy produced in GLYCOLYSIS (breakdown of glucose). ATPsynthase is the catalyst. ATP moves to the part of the cell that requires energy ATP is broken down into ADP and inorganic phosphate (Pi) and releases chemical energy. ATPase is the catalyst. ADP and phosphate are recycled and the process starts again.

5. Cells release energy by RESPIRATION Glucose is broken down to produce H20, CO2 and ENERGY. The energy is used to produce ATP from ADP and Pi. Aerobic- With Oxygen Anerobic – Without Oxygen. Both produce ATP C6 H12 O6 (glucose) + 6O2 ----------> 6CO2 + 6H2O + Energy

6. Respiration takes place in the MITOCHONDRIA Present in all EUKARYOTIC cells High energy demand cells (muscle, liver) have many mitochondria Inner membrane is folded into CRISTAE, increasing the surface area ATP is produced via stalked particles on the cristae, in the electron transport chain The KREBS CYCLE takes place in the matrix

7. Respiration is a METABOLIC PATHWAY Metabolic Pathway – Series of small reactions (respiration, photosynthesis, enzyme controlled Catabolic Reaction – Large molecules into smaller molecules, e.g. glucose in glycolysis Anabolic Reaction – Combining smaller molecules to make bigger ones using enzymes Phosphorylation – Adding phosphate to a molecule (e.g. ADP is phosphorylated to ATP) Hydrolysis – Splitting a molecule using WATER Photolysis – Splitting a molecule using LIGHT

8. REDOX Reactions If something is reduced, it has GAINED ELECTRONS and may have lost O2 or gained H2 If something is OXIDISED it has LOST ELECTRONS and may have gained O2 or lost H2. Oxidation of one thing ALWAYS involves reduction of another Enzymes that catalyse redox reactions are OXIDOREDUCTASES Respiration and photosynthesis contain redox

9. Remember – OIL RIG OIL RIG OXIDATION IS LOSS (of electrons) REDUCTION IS GAIN (of electrons)

10. GLYCOLYSIS The first stage of respiration (aerobic and anaerobic) Glycolysis splits one molecule of glucose (C6) into two smaller molecules of pyruvate (pyruvic acid - C3) Glycolysis occurs in cell cytoplasm Doesn't require oxygen

11. Respiration map GLYCOLYSIS LINK REACTION KREBS CYCLE OXIDATIVE PHOSPHORYLATION (electron transport chain)

12. Glycolysis stage ONE - Phosphorylation Glucose is PHOSPHORYLATED by adding 2 phosphates from 2 molecules of ATP to give a hexose biphosphate Hexose biphosphate is split by hydolysis 2 molecules of triose phosphate (TP) and 2 molecules of ADP are created

13. Phosphorylation GLUCOSE - 6C 2 x TRIOSE PHOSPHATE (3C) 2ATP 2ADP 2Pi H2O PHOSPHORYLATIONPHOSPHORYLATION

14. Glycolysis stage TWO - Oxidation TP is oxidised to form 2 PYRUVATE Coenzyme NAD+ collects hydrogen ions, forming 2 reduced NAD 4 ATP produced, but 2 used in phosphorylation NET GAIN of 2 ATP Pyruvate is ACTIVELY TRANSPORTED into the mitochondria for the Link Reaction Coenzyme NAD+ removes H+ and carries it to other molecules

15. Oxidation 2 x TRIOSE PHOSPHATE (3C) 2 x PYRUVATE (3C) 2NADH + H+ 2NAD+ 4H 4ADP + 4Pi 4ATP OXIDATIONOXIDATION

16. Link Reaction (Pyruvate to Acetyl CoA) One carbon atom is removed from pyruvate in the form of CO2 Remaining 2-Carbon molecule combines with CoA to produce Acetyl CoA Another oxidation happens when NAD+ collects more hydrogen ions, forming Red. NAD NO ATP IS PRODUCED Occurs in the MITOCHONDRIAL MATRIX

17. Link Reaction (Pyruvate to Acetyl CoA) For EACH glucose molecule in glycolysis, TWO pyruvate molecules are mad so the link reaction happens TWICE for EVERY GLUCOSE MOLECULE Link reaction only uses one pyruvate, so the link reaction AND the Krebs cycle happen TWICE for every glucose molecule from glycolysis

18. Link reaction (Pyruvate to Acetyl CoA) For each glucose molecule: TWO molecules of acetyl CoA go into the Krebs cycle TWO CO2 molecules are released as a waste product of respiration TWO molecules of Red. NAD are formed and go into the ELECTRON TRANSPORT CHAIN

19. Link Reaction (Pyruvate to Acetyl CoA) Pyruvate (3C) Acetyl CoA (2C) CO2 NAD+ NAD+ + H+ Coenzyme A

20. KREBS CYCLE (3 rd Stage) Occurs in the MATRIX of the MITOCHONDRIA Happens ONCE for each pyruvate molecule made in glycolysis, so TWICE for everyone glucose molecule entering respiration

21. KREBS CYCLE Acetyl CoA (2C) Citrate (6C) 5C compound Oxaloacetate (4C) CoA ATP FADH2 FA D NADH + H+ NA D NADH + H+ NAD + CO 2 NADH + H+ NAD+ CO 2

22. Krebs Cycle 1. Aceyl CoA from the link reaction combines with Oxaloacetate to form CITRATE. Coenzyme A is released back to the LINK REACTION. 2. 6C Citrate is decarboxylated (loses CO2) to give a 5C compound. 3. Both citrate and the 5C compound are dehydrogenated (lose H+) in the cycle, to reduce NAD and FAD 4. Overall, 3 Red. NAD and 1 Red. FAD are produced and enter the electron transport chain. 5. The 5C compound is decarboxylated to 4C Oxaloacetate. ATP and CO2 are released.

23. Products of the KREBS CYCLE enter the final stage of Aerobic respiration CoA is REUSED in the next link reaction Oxaloacetate is regenerated to it can be REUSED in the next Krebs cycle 2 CO2 are released as a waste product One ATP is made per cycle turn by substrate level phosphorylation 3 Red. NAD and one Red. FAD are made and enter the electron transport chain

24. Oxidative Phosphorylation happens via the Electron Transport Chain The ETC transfers energy from glycolysis, link reaction and Krebs into ADP. ADP forms ATP, which is a molecule of energy ATP Synthesis as a result of the energy released by the ETC is called Oxidative phosphorylation ETC is where MOST ATP is made. In aerobic respiration, 32 ATP molecules are made, 2 in glycolysis, 2 in Krebs and 28 in ETC ETC also REOXIDISES NAD and FAD to be resused

25. The E.T.C 1. Hydrogen atoms are released from NADH + H+ and FADH2 as the are oxidised. The H atoms split to produce protons (H+) and electrons for the chain 2. Electrons move along the chain (made up of 3 electron carriers), losing energy at each level. This energy is used to pump H+ into the space BETWEEN the inner and outer mitochondrial membrane (intermembrane space) 3. The concentraions or protons is high in the intermembrane space than in the mitochondrial matrix, making an ELECTROCHEMICAL GRADIENT

26. The E.T.C 4. The H+ then move back through th einner membrane DOWN the ELECTROCHEMICAL GRADIENT through stalked particles of the cristae. 5. This drives ATPsynthase which supplies electrical potential energy to make ATP from ADP and inorganic phosphate every 3 turns 6. H+ and e- recombine to form hydrogen, combining with molecular oxygen (half O2) from the blood to form water. Oxygen is the FINAL ELECTRON ACCEPTOR!

27. The E.T.C 1 turn of the Krebs cycle produces 4 Red. NAD (inc 1 from the link reaction) and 1 Red. FAD 2 molecules of pyruvate enter the Krebs cycle for each molecule of glucose, so 8NAD+ and 2FAD are reduced 2 Red. NAD are produced from the first part of respiration (glycolysis) Each Red. NAD produces 2.5ATP and each Red. FAD 1.5ATP 8 Red. NAD + 2 Red. NAD = 10 Red. NAD 10x2.5 = 25ATP 2 Red. FAD x 1.5 = 3ATP, so 25+3 28ATP 2 ATP from glycolysis + 2 in the Krebs = 32ATP in total

28. Anaerobic Respiration Aerobic Respiration Does not need oxygenNeeds oxygen Takes place in cytoplasmTakes place in cytoplasm AND mitochondria Uses glycolysis and alcoholic or latctate fermentation Uses glycolysis, Krebs cycle, link reaction and electron transport chain Pyruvate not completley oxidisedPyruvate oxidised in link reaction Can follow 2 metabolic pathways (alcoholic or lactate fermentation) Follows one metabolic pathway only Produces 2 ATP for every glucoseProduces 32 ATP for every glucose

29. There are TWO forms of Anerobic respiration Alcoholic fermentation – used by some microorganisms like yeast, and some plant cells when oxygen is unavailable Lactate fermentation – used by some animal cells when oxygen is unavailable Both occur in the cytoplasm, both start with the glycolysis reaction

30. Alcoholic fermentation makes alcohol 1. Glucose (6C) turns into pyruvate (3) by glycolysis 2. CO2 is removed from pyruvate to form ethanal (2C) 3. Red. NAD made in glycolysis is reoxidised and transfers 2 hydrogen atoms to ethanal to form ETHANOL 4. The reoxidised NAD is reused in glycolysis

31. ALCOHOLIC FERMENTATION Glucose (6C) Pyruvate (3C) Ethanal (2C) Ethanol (2C) Glycolys is 2ADP 2ATP 2ADP NAD+ NADH + H+ CO2 NADH + H+ NAD+

32. Alcoholic fermentation is used in INDUSTY Brewing – Yeasts ferment fruit or grain to produce alcoholic drinks (wine, beer, cider etc) Breadmaking – Yeasts produce CO2, which helps bread to ruse. The alcohol evaporates during the baking process Fermentation reactions are carried out on an industrial scale in fermenters or bioreactors.

33. Lactate Fermentation occurs in Animal Cells SOME animal cells can respire without oxygen (for a short time only) 1. Glycolysis produces pyruvate 2. Pyruvate is reduced to lactate (lactic acid) by adding 2 H atoms from Red. NAD 3. NAD is returned to glycolysis to be used again

34. Lactate Fermentation Glucose Pyruvate Lactate (lactic acid) Glycolysis 2ADP 2ATP NAD+ NADH + H+ NAD+

35. Anaerobic respiration occurs in Muscle Cells during excersise In vigorous excersise, the supply of pyruvate from glycolysis is MORE THAN the oxygen supply available for the latter stages of aerobic respiration. This causes anaerobic respiration by lactate fermentation Lactate build up in the muscles is removed by the blood. When O2 is available again, the LIVER converts lactate back to pyruvate or glucose and then glycogen for storage. The amount of O2 needed for this is “Oxygen Debt”

36. Anaerobic Respiration is NOT very Efficient In aerobic respiration 32 molecules of ATP are produced for every glucose molecule In anaerobic respiration, only 2 ATP molecules are made (during glycolysis) Aerobic respiration releases 16 times more energy than anaerobic respiration

37. Rate of Respiration The amount of oxygen uptake and the volume of CO2 produced are indicators of the respiration rate. A RESPIROMETER can be used to measure oxygen uptake.

38. RESPIROMETER Any CO2 produced by an organism in a respirometer is absorbed by NaOH present in the test tube Any decrease in air volume of the manometer is from O2 uptake or the organism O2 uptake reduces the pressure in the tube, so a coloured liquid moves towards the test tube Distance moved by the liquid in a given time is measured and used to calculate rate of respiration A control tube must contain a mass of equal surface area to the organism in the test tube The system must be air-tight to prevent external pressure fluctuations from skewing results

39. RQ Values Volume of CO2 produced divided by Volume of O2 used Human RQ usually between 0.7 and1 High RQ's mean an organism is short of oxygen If an organism is respiring lipids, its RQ will be LOWER than 1 as more O2 is needed to oxidise fat than carbohydrates Plants may have a low RQ as the CO2 released in respiration is used in photosynthesis and so not measured

40. RQ Values Respiratory SubstrateRQ Lipids (Triglycerides)0.7 Proteins or amino acids0.9 Carbohydrates (e.g. Glucose)1 Anaerobic respiration of carbohydrates >1

41. Temperature + Respiration Rate For every 10C rise in temperate, respiration rate doubles After 45C, respiration rate begins to fall as vital proteins (e.g. enzymes) become denatured For ectothermic organisms, temperature greatly affects respiration rate. For endothermic organisms, it is less important