CHAPTER 12- ENERGY AND RESPIRATION .pptx

A ppt about energy and respiration

1. ENERGY AND RESPIRATION A 2 Edexcel Biology Xavier DANIEL, Ph.D.

2. Introduction Muscle contraction needs ATP All activities of cells need ATP as well How is ATP made available? Cell respiration = transfer of energy from nutrients to ATP ATP provides energy for cells’ needs

3. Introduction Oxygen Two kinds of cell respiration Depending on availability of Oxygen Aerobic respiration Anaerobic respiration Available Not available

4. Introduction Oxygen Two kinds of cell respiration Depending on availability of Oxygen Aerobic respiration Anaerobic respiration Available Not available Common steps

5. Introduction Aerobic respiration and Combustion In aerobic respiration, glucose oxidised to CO 2 , O 2 is reduced into water + a LOT of energy (ATP) produced Word equation Glucose + Oxygen Carbon dioxide + water Chemical equation (unbalanced) C 6 H 12 O 6 + O 2 CO 2 + H 2 O (+ENERGY) (+ENERGY) Balanced chemical equation C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 H 2 O (+ENERGY) Simplified version (IGCSE) Actually many steps

6. Introduction Aerobic respiration and Combustion Sometimes, aerobic respiration is compared to combustion WRONG Combustion releases energy from fuel as HEAT in one step-reaction This would be d angerous/disastrous for cells In aerobic respiration, MANY steps occur Each step catalysed by one enzyme Energy released in small quantities at several steps Much energy made available Trapped in molecules of ATP BUT some energy lost as heat Respiration = main source of heat in many organisms

7. ATP AND CELLULAR RESPIRATION

8. ATP, the universal energy currency

9. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Location cytoplasm matrix across cristae aerobic ions

10. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Glycolysis happens in the cytoplasm Glucose (6 carbon) is broken down by oxidation into 2 pyruvate (3 carbon) Does not require oxygen Four steps in glycolysis Phosphorylation Lysis Oxidation ATP formation Glycolysis

11. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Glycolysis happens in the cytoplasm Glucose (6 carbon) is broken down by oxidation into 2 pyruvate (3 carbon) Does not require oxygen Four steps in glycolysis Phosphorylation Lysis Oxidation ATP formation - Glucose is phosphorylated 2 times - Formation of fructose bisphosphate - Two phosphates come from 2 ATP Glucose + 2 ATP Fructose bisphosphate + 2 ADP Two ATP are consumed Glycolysis

12. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Glycolysis happens in the cytoplasm Glucose (6 carbon) is broken down by oxidation into 2 pyruvate (3 carbon) Does not require oxygen Four steps in glycolysis Phosphorylation Lysis Oxidation ATP formation Fructose bisphosphate is splitted into 2 triose phosphate Triose = 3-Carbon sugar Fructose bisphosphate 2 triose phosphate Glycolysis

13. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Glycolysis happens in the cytoplasm Glucose (6 carbon) is broken down by oxidation into 2 pyruvate (3 carbon) Does not require oxygen Four steps in glycolysis Phosphorylation Lysis Oxidation ATP formation 2 triose phosphate oxidised into 2 pyruvate A dehydrogenase transfers 2 H + and 2 e - from TP to acceptor Acceptor of H + and e - = co-enzyme = NAD + NAD + = N icotin a mide d inucleotide 2 NAD + are reduced into NADH + H + 2 triose phosphate + 2 NAD + 2 pyruvate + 2 NADH + H + NAD is not NADPH NAD in Cell respiration NADP in photosynthesis NADH + H + = NADH 2 Glycolysis

14. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Glycolysis happens in the cytoplasm Glucose (6 carbon) is broken down by oxidation into 2 pyruvate (3 carbon) Does not require oxygen Four steps in glycolysis Phosphorylation Lysis Oxidation ATP formation Transfer of H + during oxidation releases energy Energy used to combine ADP + Pi into ATP Phosphorylation of ADP 2 times per molecule of triose phosphate 4 ADP + 4 Pi 4 ATP Four ATP are synthesised Glycolysis

15. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Four ATP are synthesised Two ATP are consumed Two ATP are made (per molecule of glucose) Glucose + 2 NAD + + 2 ADP + 2 Pi 2 pyruvate + 2 NADH 2 + 2 ATP Glycolysis

16. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Called “ link reaction ” because it connects/links glycolysis to Krebs cycle Krebs cycle happens in the matrix of mitochondria First step of link reaction = active transport from the cytoplasm into the mitochondrial matrix Molecule needed for Krebs cycle = 2 –carbon molecule Pyruvate = 3-carbon molecule Link reaction changes 2 pyruvate into two 2-carbon molecule = 2 acetyl groups Loss of 2 carbon in the form of 2 CO 2 = decarboxylation 2 pyruvate are also oxidised AND 2 NAD + are reduced into 2 NADH 2 2 Acetyl groups have to be brought to Krebs cycle 2 acetyl groups need a transporter = Coenzyme A Formation of 2 acetyl coenzyme A 2 pyruvate + 2 NAD + + 2 coA 2 acetyl coA + 2 CO 2 + 2 NADH 2 X2 Link reaction

17. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Krebs cycle happens in the matrix of mitochondrion Main point is to produce reduced molecules = NADH 2 and FADH 2 Also produces CO 2 and ATP Three steps in Krebs cycle Make citrate out of acetyl group + oxaloacetate Oxidation of citrate* into a -ketoglutarate Oxidation of a -ketoglutarate into oxaloacetate = regeneration of oxaloacetate Active transport Krebs cycle Discovered by Hans Krebs * Also named citric acid cycle

18. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Krebs cycle happens in the matrix of mitochondrion Main point is to produce reduced molecules = NADH 2 and FADH 2 Also produces CO 2 and ATP Three steps in Krebs cycle Make citrate out of acetyl group + oxaloacetate Oxidation of citrate into a -ketoglutarate Oxidation of a -ketoglutarate into oxaloacetate = regeneration of oxaloacetate Krebs cycle Active transport Acetyl co A reacts with a 4-carbon organic acid (= oxaloacetate ) to produce 6-carbon molecule (= citric acid or citrate ) + coenzyme A Coenzyme A recycled for another link reaction 2 pyruvate per molecule of glucose Multiply by two

19. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Krebs cycle happens in the matrix of mitochondrion Main point is to produce reduced molecules = NADH 2 and FADH 2 Also produces CO 2 and ATP Three steps in Krebs cycle Make citrate out of acetyl group + oxaloacetate Oxidation of citrate into a -ketoglutarate Oxidation of a -ketoglutarate into oxaloacetate = regeneration of oxaloacetate Krebs cycle Active transport Citrate oxidised into a - ketoglutarate And NAD + reduced into NADH 2 a - ketoglutarate = 5-carbon molecule citrate is also decarboxylated : formation of CO 2

20. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Krebs cycle happens in the matrix of mitochondrion Main point is to produce reduced molecules = NADH 2 and FADH 2 Also produces CO 2 and ATP Three steps in Krebs cycle Make citrate out of acetyl group + oxaloacetate Oxidation of citrate into a -ketoglutarate Oxidation of a-ketoglutarate into oxaloacetate = regeneration of oxaloacetate Krebs cycle Active transport a - ketoglutarate oxidised into oxaloacetate oxaloaxetate is regenerated , available for next turn of Krebs cycle And 2 NAD + reduced into 2 NADH 2 And FAD + reduced into FADH 2 oxaloaxetate = 4-carbon molecule a -ketoglutarate is also decarboxylated : formation of CO 2

21. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Krebs cycle happens in the matrix of mitochondrion Main point is to produce reduced molecules = NADH 2 and FADH 2 Also produces CO 2 and ATP Krebs cycle 1 acetylcoA + 3 NAD + + FAD + + ADP + Pi 2 CO 2 + 3 NADH 2 + FADH 2 + ATP Active transport Per acetyl coA molecule 2 acetylcoA + 6 NAD + + 2FAD + + 2ADP + 2Pi 4 CO 2 + 6 NADH 2 + 2 FADH 2 + 2 ATP Per glucose molecule

22. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Krebs cycle happens in the matrix of mitochondrion Main point is to produce reduced molecules = NADH 2 and FADH 2 Also produces CO 2 and ATP Krebs cycle Triglycerides can be respired too Triglycerides broken down to glycerol + 3 fatty acids Hydrocarbon chain of fatty acids “cut up” into several 2-carbon fragments 2-carbon fragments linked to coenzyme A Fed to Krebs cycle Triglycerides feed many more Krebs cycles than glucose Triglycerides provide more energy than glucose Several 2-carbon molecules Fatty acids

23. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Electron transport chain Transport of electrons from NADH 2 and FADH 2 up to oxygen along electron transport chain Electrons carriers in the inner membrane of mitochondrion Two sources of electrons: - NADH 2 oxidised to NAD + - FADH 2 oxidised to FAD + Inner membrane Intermembrane space Matrix

24. Aerobic respiration A 2 Edexcel Biology Xavier DANIEL, Ph.D. Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Generation of H + ions gradient across inner membrane of mitochondrion Transport of electrons in the ETC releases energy Energy used to actively pump H + ions from matrix into intermembrane space of mitochondrion Accumulation of H+ ions inside intermembrane space of mitochondrion Creation of H + ions gradient from matrix to intermembrane space of mitochondrion Intermembrane space Matrix Inner membrane

25. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Chemiosmosis H + ions naturally “want” to come back to the matrix down their concentration gradient Cannot cross the hydrophobic ( non-polar ) part of the phospholipid bilayer of the inner membrane (H + ions are polar ) H + ions flow back to matrix though specific channel: Chemiosmosis by facilitated diffusion Chemiosmosis releases energy Energy used by enzyme coupled to H + channel= ATP synthetase ATP synthetase phosphorylates ADP: formation of ATP Intermembrane space Matrix Inner membrane

26. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Oxidative phosphorylation Phosphorylation of ADP into ATP is dependent on oxidation of NAD + and FAD + during G/LR/KC Phosphorylation of ADP into ATP is dependent on oxidation of NADH 2 and FADH 2 “ Oxidative phosphorylation ” Intermembrane space Matrix Inner membrane

27. Aerobic respiration Aerobic respiration made of 4 main steps 1. Glycolysis 2. Link reaction 3. Krebs cycle 4. Electron transport chain + More Formation of water Transport of electrons from NADH 2 and FADH 2 up to oxygen Transport of H + ions from NADH 2 and FADH 2 up to oxygen ½ O 2 + 2 H + ions + 2 e - H 2 O = Water

28. Aerobic respiration Review ATP produced = 40 – 2 = 38

29. Anaerobic respiration or Fermentation Anaerobic respiration also starts with Glycolysis See slides # 13 - 18

30. Anaerobic respiration or Fermentation If oxygen not available, cells still need energy Turn to anaerobic respiration Anaerobic respiration In flowering plants and yeast Alcoholic fermentation In animals Lactic acid fermentation Word equation Glucose Ethanol + Carbon dioxide Chemical equation (unbalanced) C 6 H 12 O 6 CH 3 CH 2 OH + CO 2 (+energy) Balanced chemical equation C 6 H 12 O 6 2 CH 3 CH 2 OH + 2 CO 2 (+energy) (+energy) Word equation Glucose Lactic acid Chemical equation (unbalanced) C 6 H 12 O 6 CH 3 CHOHCOOH (+energy) (+energy) (+energy) Balanced chemical equation C 6 H 12 O 6 2 CH 3 CHOHCOOH

31. Anaerobic respiration or Fermentation Efficiency of anaerobic respiration is way lower than aerobic respiration’s 2 ATP instead of 38

32. During non vigorous exercise, enough Oxygen and Glucose are provided by blood to the muscles Aerobic respiration occurs all along the exercise During vigorous exercise, not enough Oxygen and Glucose are provided by blood to the muscles Anaerobic respiration starts at the onset of the exercise Lactic acid accumulates in the muscles Causing cramps Body needs to get rid of lactic acid Fate of lactic acid in Anaerobic respiration

33. How to get rid of lactic acid? - What: Break it down into glucose - Where: In the liver - How: Aerobic respiration During and after vigorous exercise, keep heart rate fast to transport lactic acid from muscles to liver During and after vigorous exercise, keep breathing rate fast to transport Oxygen and glucose to liver Aerobic respiration Fate of lactic acid in Anaerobic respiration

34. Start of vigorous exercise End of vigorous exercise Fate of lactic acid in Anaerobic respiration