1. Biology – Premed Windsor University School of Medicine Biology Chapter 8 Cellular Respiration

2. Pre Med – Biology Chapter 8 Cellular Respiration There is more to lectures than the power point slides! Engage your mind

3. Cellular Respiration 1

5. It is worth studying this presentation thoroughly because it is essential for an understanding of all the activities of living cells and organisms 2 THE CONCEPT OF ‘Cellular Respiration’ IS CENTRAL TO ALL LIVING PROCESSES

6. All living cells are made up of chemical substances The processes of living involve reactions between the substances A reaction is an event which produces a change in a substance For example, a reaction between carbon and oxygen (such as burning coal in air) changes the carbon in the coal, and oxygen in the air into carbon dioxide 3 This reaction can be represented by the equation C + O 2 CO 2 carbonoxygencarbon dioxide

8. The reaction between carbon and oxygen also releases energy in the form of heat and light (flames) Living organisms get their energy from reactions like this (but not reactions which are violent enough to produce flames) 5

9. 7 One of the energy-producing reactions is called respiration (Respiration is not the same thing as breathing) The chemical reactions of respiration take place in all living cells The reaction takes place between oxygen and a substance which contains carbon. The reaction produces carbon dioxide and water, and releases energy

10. The carbon-containing substances come from FOOD The oxygen comes from the AIR (or water) The energy is used to drive other chemical reactions taking place in cells One example of this is the release of energy in muscle cells to make them contract and produce movement 8

11. 9 One example of an energy-producing reaction in cells is the breakdown of sugar when it combines with oxygen This can be represented by the equation C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O +energy sugar (glucose) oxygencarbon dioxide water This means that one molecule of sugar reacts with six molecules of oxygen to produce six molecules of carbon dioxide and six molecules of water. Energy is released during this process

12. Respiration supplies the energy for muscle contraction germination cell division chemical changes in cells Some examples of the use of energy in organisms 10

13. The blood stream brings food and oxygen to the muscle cells. Respiration occurs in the cells and releases energy which…… shoulder blade upper arm bone lower arm bones Energy use in muscle contraction 11

14. Glucose and oxygen react to produce energy for muscle contraction 4 RESPIRATION 5 Carbon dioxide is carried to the lungs by the blood 15 One example of respiration in ourselves 1. Air taken in 1.Food taken in 2. The lungs absorb oxygen from the air 2.The stomach and intestine digest food. One of the products is glucose 3.The blood stream carries glucose and oxygen to the muscles

15. Question 1 What is the most important point about respiration? (a) it uses oxygen (b) It produces energy (c) It produces carbon dioxide (d) It needs food and air 16

16. Question 2 In which part of the human body is respiration most likely to be occurring? (a) The lungs (b) The heart (c) The muscles (d) All of these 17

17. Question 3 Which of these are waste products of respiration? (a) Carbon dioxide (b) Water (c) Oxygen (d) Nitrogen 18

18. Question 4 Which of the following would be reliable indicators of respiration in a living organism? (a) Output of water vapour (H 2 O) (b) Output of carbon dioxide (CO 2 ) (c) Uptake of oxygen (O 2 ) (d) Production of energy 19

19. Question 5 Which of the following statements is correct? (a) We breathe in air (b) We breathe in oxygen (c) We breathe out air (d) We breathe out carbon dioxide 20

20. What Is ATP? Energy used by all Cells Adenosine Triphosphate Organic molecule containing high- energy Phosphate bonds

21. Chemical Structure of ATP 3 Phosphates Ribose Sugar Adenine Base

22. How Do We Get Energy From ATP? By breaking the high- energy bonds between the last two phosphates in ATP

23. What is the Process Called? HYDROLYSIS (Adding H 2 O) H2OH2O

24. How Does That Happen? An Enzyme!

25. How is ATP Re-Made? The reverse of the previous process occurs. Another Enzyme is used! ATP Synthetase

26. The ADP-ATP Cycle ATP-ase ATP Synthetase Copyright Cmassengale

27. When is ATP Made in the Body? During a Process called Cellular Respiration that takes place in both Plants & Animals

28. Cellular Respiration Includes pathways that require oxygenIncludes pathways that require oxygen Glucose is oxidized and O 2 is reducedGlucose is oxidized and O 2 is reduced Glucose breakdown is therefore an oxidation-reduction reactionGlucose breakdown is therefore an oxidation-reduction reaction Breakdown of one glucose results in 36 to 38 ATP moleculesBreakdown of one glucose results in 36 to 38 ATP molecules

29. Overall Equation for Cellular Respiration 6CO 2 + 6H 2 0 + e - + 36-38 ATP’s C 6 H 12 O 6 + 6O 2 YIELDS

30. What Type of Process is Cellular Respiration? An Oxidation-Reduction Process or REDOX ReactionAn Oxidation-Reduction Process or REDOX Reaction Oxidation of GLUCOSE --> CO 2 + H 2 O (e - removed from C 6 H 12 O 6 )Oxidation of GLUCOSE --> CO 2 + H 2 O (e - removed from C 6 H 12 O 6 ) Reduction O 2 to H 2 O (e - passed to O 2 )Reduction O 2 to H 2 O (e - passed to O 2 )

31. What Carries the Electrons? NAD + (nicotinadenine dinucleotide) acts as the energy carrierNAD + (nicotinadenine dinucleotide) acts as the energy carrier NAD + is a coenzymeNAD + is a coenzyme It’s Reduced to NADH when it picks up two electrons and one hydrogen ionIt’s Reduced to NADH when it picks up two electrons and one hydrogen ion

33. Are There Any Other Electron Carriers? YES! Another Coenzyme!YES! Another Coenzyme! FAD+ (Flavin adenine dinucleotide) FAD+ (Flavin adenine dinucleotide) Reduced to FADH 2Reduced to FADH 2

34. Other Cellular Respiration Facts Metabolic Pathway that breaks down carbohydratesMetabolic Pathway that breaks down carbohydrates Process is Exergonic as High-energy Glucose is broken into CO 2 and H 2 OProcess is Exergonic as High-energy Glucose is broken into CO 2 and H 2 O Process is also Catabolic because larger Glucose breaks into smaller moleculesProcess is also Catabolic because larger Glucose breaks into smaller molecules

35. What are the Stages of Cellular Respiration? GlycolysisGlycolysis The Krebs CycleThe Krebs Cycle The Electron Transport ChainThe Electron Transport Chain

37. Where Does Cellular Respiration Take Place? It actually takes place in two parts of the cell:It actually takes place in two parts of the cell: Glycolysis occurs in the Cytoplasm Krebs Cycle & ETC Takeplace in the Mitochondria Krebs Cycle & ETC Take place in the Mitochondria

38. Diagram of the Process Occurs in Cytoplasm Occurs in Matrix Occurs across Cristae

39. Glycolysis Summary Takes place in the Cytoplasm Anaerobic (Doesn’t Use Oxygen) Requires input of 2 ATP Glucose split into two molecules of Pyruvate or Pyruvic Acid Also produces 2 NADH and 4 ATPAlso produces 2 NADH and 4 ATP Pyruvate is oxidized to Acetyl CoA and CO 2 is removedPyruvate is oxidized to Acetyl CoA and CO 2 is removed

40. Glycolysis

46. Glycolysis Diagram

47. Oxidation of Pyruvate to Acetyl CoA

48. Citric Acid Cycle

53. A Little Krebs Cycle History Discovered by Hans Krebs in 1937Discovered by Hans Krebs in 1937 He received the Nobel Prize in physiology or medicine in 1953 for his discoveryHe received the Nobel Prize in physiology or medicine in 1953 for his discovery Forced to leave Germany prior to WWII because he was JewishForced to leave Germany prior to WWII because he was Jewish

54. Krebs Cycle Summary Requires Oxygen (Aerobic)Requires Oxygen (Aerobic) Cyclical series of oxidation reactions that give off CO 2 and produce one ATP per cycleCyclical series of oxidation reactions that give off CO 2 and produce one ATP per cycle Turns twice per glucose moleculeTurns twice per glucose molecule Produces two ATPProduces two ATP Takes place in matrix of mitochondriaTakes place in matrix of mitochondria

55. Krebs Cycle Summary Each turn of the Krebs Cycle also produces 3NADH, 1FADH 2, and 2CO 2Each turn of the Krebs Cycle also produces 3NADH, 1FADH 2, and 2CO 2 Therefore, For each Glucose molecule, the Krebs Cycle produces 6NADH, 2FADH 2, 4CO 2, and 2ATPTherefore, For each Glucose molecule, the Krebs Cycle produces 6NADH, 2FADH 2, 4CO 2, and 2ATP

56. Krebs Cycle ATP NETS: 3NADH, 1ATP, 1FADH 2, & 2CO 2

58. Electron Transport Chain

59. Electron Transport Chain Summary 34 ATP Produced34 ATP Produced H 2 O ProducedH 2 O Produced Occurs Across Inner Mitochondrial membraneOccurs Across Inner Mitochondrial membrane Uses coenzymes NAD+ and FAD+ to accept e- from glucoseUses coenzymes NAD+ and FAD+ to accept e- from glucose NADH = 3 ATP’sNADH = 3 ATP’s FADH 2 = 2 ATP’sFADH 2 = 2 ATP’s

65. Fermentation Occurs when O 2 NOT present (anaerobic)  Occurs when O 2 NOT present (anaerobic)  Called Lactic Acid fermentation in muscle cells (makes muscles tired)  Called Alcoholic fermentation in yeast (produces ethanol)  Nets only 2 ATP

66. Anaerobic Respiration 23

67. The process of respiration described so far has been defined as the release of energy when foodstuffs such as glucose react with oxygen to produce carbon dioxide and water. This form of respiration, which needs oxygen, is called aerobic respiration. There is another form of respiration which does not need oxygen and is called anaerobic respiration. In anaerobic respiration, glucose is still broken down to carbon dioxide with the release of energy, but without the involvement of oxygen The glucose is not completely broken down to CO 2 and H 2 O but to CO 2 and alcohol (ethanol). 24

68. Anaerobic respiration can be represented by the equation C 6 H 12 O 6 2C 2 H 5 OH + 2CO 2 glucose alcohol energy For example, our own muscles resort to anaerobic respiration when oxygen is not delivered to them fast enough. The energy released by anaerobic respiration is considerably less than the energy from aerobic respiration. Anaerobic respiration takes place at some stage in the cells of most living organisms. 25

69. Micro-organisms Anaerobic respiration is widely used by many micro-organisms such as bacteria and yeasts. Bacteria and yeasts are microscopic single-celled organisms. Bacteria are to be found everywhere, in or on organisms, in water, air and soil Yeasts are usually found in close association with vegetable matter such as fruit 26

70. Bacteria 0.002mm a single bacterium there are many species of bacteria and they have different shapes and sizes cell wall nucleus cytoplasm 27

71. Aerobic and anaerobic bacteria Bacteria which need oxygen in order to respire are called aerobic bacteria. Aerobic bacteria are likely to be found in the air, water and soil where oxygen is available Bacteria which can respire without needing oxygen are called anaerobic bacteria Anaerobic bacteria are to be found in situations where oxygen is lacking, such as in stagnant water, waterlogged soils or the intestines of animals 28

72. Yeast

74. Fermentation One form of anaerobic respiration in bacteria and yeasts is called fermentation. During fermentation, sugar is broken down to alcohol and carbon dioxide The reaction described in slide 25 is an example of fermentation Fermentation is involved in brewing and wine-making 30

75. Yeasts 0.005mm single yeast cell Yeast cells dividing cell wall nucleus cytoplasm vacuole 29

76. Wine making Grapes are crushed and the sugar they contain is fermented by yeasts to produce alcohol and carbon dioxide. The carbon dioxide usually escapes but if the wine is bottled before fermentation is complete, the carbon dioxide dissolves and escapes as bubble when the bottle is opened This is the case with ‘sparkling’ wines such as Champagne Different varieties of grape produce different types of wine 31

77. Black grapes growing in a vineyard © Ilan’s Wine Making 32

78. Brewing In brewing beer, a sugary product (malt) is dissolved out of germinating barley Yeast is added to this solution and fermentation begins, producing alcohol and carbon dioxide Some of the carbon dioxide escapes but the rest dissolves in the beer when it is bottled or put into casks When the bottles or casks are opened, the dissolved CO 2 escapes as bubbles 33

79. Beer fermenting ©Stuart Boreham/CEPHAS 34

80. Baking In baking, yeast is added to a mixture of flour and water, made into the form of a dough The yeast first changes the flour starch into sugar and then ferments the sugar into alcohol and CO 2 The CO 2 forms bubbles in the dough which cause it to expand (‘rise’) When the dough is baked, the heat evaporates the alcohol but makes the trapped bubbles expand giving the bread a ‘light’ texture 35

81. Dough rising 36 The yeast is mixed with the dough After 1 hour in a warm place the dough has risen as a result of the carbon dioxide produced by the yeast

82. The ‘holes’ in the bread are made by the carbon dioxide bubbles. This gives the bread a ‘light’ texture 37

83. Question 1 Which statements are correct ? Anaerobic respiration is different from aerobic respiration because a it produces CO 2 b it does not need glucose c it does not need oxygen d it produces less energy 38

84. Question 2 In what circumstances do our muscle use anaerobic respiration ? a When insufficient glucose reaches the muscles b When the carbon dioxide level increases c When insufficient oxygen reaches the muscles d When we are asleep 39

85. Question 3 Anaerobic bacteria are most likely to be found a in the middle of a compost heap b in the air c in fast-flowing streams d on the surface of the skin 40

86. Question 4 In which of the following is the production of CO 2 more important than the production of alcohol ? a Brewing beer b Fermenting grape juice c Making bread d Bottling wine 41