EXAM 1 RESULTS 90-100 3 students 80-89 5 students 70-79 7 students 60-69 3 students 50-60 2 students No one got bel

1. EXAM #1 RESULTS90-100 = 3 students80-89 = 5 students70-79 = 7 students60-69 = 3 students50*-60 = 2 students*No one got below a 50 1 students did not take the test

2. How would you rate the quality of this course so far? 18 completed; 2 not completes Average was 8.5 Comments: �Lab to get better� �When presenting the material going a little more in depth with typical examples would improve my learning skills��� �Would be better if recently taken chemistry� �I would like the lecture to go a little slower so I can copy the lecture notes�

3. Comments cont. �I like the overhead powerpoint presentations� �Slow down a little bit� �Better coordination between lab and lecture� �I like the video clips� �Sync with lab� �I like all the material posted on the web. It makes it easy to study� �Make lectures more interactive � I like the group Quizzes�

4. Review Ch. 6 Group Question/Answer Session

5. Chapter 9 Biology

6. Cellular Respiration 1. Cellular respiration includes the various metabolic pathways that break down carbohydrates and other metabolites and build up ATP. 2. Aerobic respiration begins with glucose and oxygen, and ends with CO2 and H2O. Organic Compound + Oxygen ----> Carbon Dioxide + Water + Energy Remember: Organic compounds store energy in their arrangement of atoms. With the help of enzymes, a cell systematically degrades complex organic molecules that are rich in potential energy to simpler waste products that have less energy. Some of the energy taken out of chemical storage can be used to do work; the rest is dissipated as heat. Remember: Organic compounds store energy in their arrangement of atoms. With the help of enzymes, a cell systematically degrades complex organic molecules that are rich in potential energy to simpler waste products that have less energy. Some of the energy taken out of chemical storage can be used to do work; the rest is dissipated as heat.

8. As we learned last Tuesday, metabolic pathways that release stored energy by breaking down complex molecules are called catabolic pathways. The most prevalent and efficient catabolic pathway is cellular respiration in which oxygen is consumed as a reactant along with the organic fuel. In eukaryotic cells, mitochondria house most of the metabolic equipment for cellular respiration. Remember: use of an exergonic reaction (spontaneous) to drive an endergonic reaction (requires energy) As we learned last Tuesday, metabolic pathways that release stored energy by breaking down complex molecules are called catabolic pathways. The most prevalent and efficient catabolic pathway is cellular respiration in which oxygen is consumed as a reactant along with the organic fuel. In eukaryotic cells, mitochondria house most of the metabolic equipment for cellular respiration. Remember: use of an exergonic reaction (spontaneous) to drive an endergonic reaction (requires energy)

10. Redox Reactions Based on the transfer of electrons during the chemical reaction. The relocation of electrons release the energy stored in food molecules, and this energy is used to synthesize ATP. These electron transfers are called oxidation-reduction reactions (redox reactions). The loss of electrons from one substance is called oxidation The addition of electrons to another substance is called reduction (reduce the amount of positive charge)

11. B. NAD+ Is a Carrier of Electrons Electrons received by NAD+ and FAD are high-energy electrons and are carried to the electron transport system. Remember: we are discovering how cells use energy stored in food molecules to make ATP. Glucose and other organic fuels are broken down gradually in a series of steps each one catalyzed by an enzyme. At key steps, hydrogen atoms are stripped from glucose but they are not transferred directly to oxygen. They are passed 1st to a co-enzyme called NAD+ (nicotinamide adenine dinucleotide). NAD+ functions as an oxidizing agent during respiration. READ SLIDERemember: we are discovering how cells use energy stored in food molecules to make ATP. Glucose and other organic fuels are broken down gradually in a series of steps each one catalyzed by an enzyme. At key steps, hydrogen atoms are stripped from glucose but they are not transferred directly to oxygen. They are passed 1st to a co-enzyme called NAD+ (nicotinamide adenine dinucleotide). NAD+ functions as an oxidizing agent during respiration. READ SLIDE

12. Enzymes called dehydrogenases remove a pair of hydrogen atoms from the substrate, ie. Sugar. The enzyme delivers the 2 electrons along with 1 proton to its coenzyme NAD+. The other proton is released as a H ion into the surrounding solution. Though the oxidized form NAD+ has a positive charge the reduced form NADH is neutral. The enzymatic transfer of 2 electrons and one proton from some organic substrate to NAD+ reduces the NAD+ to NADH. Most of the electrons removed from food are transferred initially to NAD+. Electrons lose very little of their potential energy when they are transferred from food to NAD+. Each NADH molecule formed during respiration represents stored energy that can be tapped to make ATP.Enzymes called dehydrogenases remove a pair of hydrogen atoms from the substrate, ie. Sugar. The enzyme delivers the 2 electrons along with 1 proton to its coenzyme NAD+. The other proton is released as a H ion into the surrounding solution. Though the oxidized form NAD+ has a positive charge the reduced form NADH is neutral. The enzymatic transfer of 2 electrons and one proton from some organic substrate to NAD+ reduces the NAD+ to NADH. Most of the electrons removed from food are transferred initially to NAD+. Electrons lose very little of their potential energy when they are transferred from food to NAD+. Each NADH molecule formed during respiration represents stored energy that can be tapped to make ATP.

13. C. Metabolic Pathways Are Required Glycolysis is the breakdown of glucose to two molecules of pyruvate. 1) Enough energy is released for immediate buildup of two ATP. 2) Glycolysis takes place outside the mitochondria and does not utilize oxygen. The process of cellular respiration involves glysolysis, the kreb�s cycle and electron transport. Glycolysis and the kreb�s cycle are catabolic pathways that decompose glucose and other organic fuels. Some of the steps are redox reactions in which dehydrogenase enzymes transfer electrons from substrates to NAD+ forming NADH. The process of cellular respiration involves glysolysis, the kreb�s cycle and electron transport. Glycolysis and the kreb�s cycle are catabolic pathways that decompose glucose and other organic fuels. Some of the steps are redox reactions in which dehydrogenase enzymes transfer electrons from substrates to NAD+ forming NADH.

15. C. Metabolic Pathways Are Required The Transition Reaction: pyruvate is oxidized to an acetyl group and CO2 is removed.

17. C. Metabolic Pathways Are Required The Krebs Cycle 1) This series of reactions gives off CO2 and produces ATP. 2) Produces two immediate ATP molecules per glucose molecule.

19. C. Metabolic Pathways Are Required The Electron Transport System 1) Series of carriers accepts electrons from glucose; electrons are passed from carrier to carrier until received by oxygen. 2) Electrons pass from higher to lower energy states, energy is released and stored for ATP production. 3) Oxygen (O2) is reduced to water (H2O).

21. Outside the Mitochondria: Glycolysis

22. A. Glycolysis: 1. Occurs in the cytosol outside the mitochondria. 2. The breakdown of glucose to 2 pyruvate molecules. 3. Universal in organisms; therefore, most likely evolved before Krebs cycle and electron transport system.

23. B. Energy Investment Steps 1. Glycolysis begins with addition of 2 phosphate groups, activating glucose to react. 2. Two separate reactions use 2 ATP. 3. Glucose, a C6 molecule, splits into two C3 molecules, each with a phosphate group.

24. C. Energy Harvesting Steps Substrate Level Phosphorylation Substrate level phosphorylation is a mode of ATP synthesis that occurs when an enzyme transfers a phosphate group from a substrate molecule to ADP. Some ATP is made by direct enzymatic transfer of a phosphate group from a substrate to ADP. The phosphate donor in this case is PGAP which is formed from the breakdown of sugar during glycolysis. Substrate level phosphorylation is a mode of ATP synthesis that occurs when an enzyme transfers a phosphate group from a substrate molecule to ADP. Some ATP is made by direct enzymatic transfer of a phosphate group from a substrate to ADP. The phosphate donor in this case is PGAP which is formed from the breakdown of sugar during glycolysis.

25. Glycolysis MamboGlycolysis Mambo

26. Glycolysis Mambo Do not let the chemical details block your view of glycolysis as a source of ATP and NADH Just sing!

28. Inside the Mitochondria: Completion of Aerobic Respiration Pyruvate enters mitochondria. Glycolysis releases less than a quarter of the chemical energy stored in glucose. Most of the energy remains stocked in the 2 molecules of pyruvate. I molecular oxygen is present the pyruvate enters the mitochondrion where the enzymes of the krebs cycle complete the oxidation of the organic fuel. Glycolysis releases less than a quarter of the chemical energy stored in glucose. Most of the energy remains stocked in the 2 molecules of pyruvate. I molecular oxygen is present the pyruvate enters the mitochondrion where the enzymes of the krebs cycle complete the oxidation of the organic fuel.

29. A. Aerobic Respiration: 1. Involves the Transition reaction, the Krebs cycle, and the Electron transport system. 2. Process in which pyruvate from glycolysis is broken down completely to CO2 and H2O. 3. Takes place inside mitochondria.

31. C. Transition Reaction Releases CO2 1. Transition reaction connects glycolysis to the Krebs cycle. 2. In this reaction, pyruvate is converted to a two-carbon acetyl group attached to coenzyme A.

32. C. Transition Reaction Releases CO2 3. This oxidation reaction removes electrons from pyruvate by dehydrogenase using NAD+ as coenzyme. 4. Reaction occurs twice for each original glucose molecule.

33. D. The Krebs Cycle Finishes Glucose Breakdown 1. Krebs cycle reactions occur in matrix of mitochondria. 2. Cycle is named for Sir Hans Krebs, who received Nobel Prize for identifying these reactions. 3. Cycle begins by adding C2 acetyl group to C4 molecule, forming citrate; also called the citric acid cycle.

34. We will talk about the electron transport system next. We will talk about the electron transport system next.

37. E. The Electron Transport System Produces Most ATP Electron transport system is located in cristae of mitochondria; consists of carriers that pass electrons. Oxygen serves as terminal electron acceptor and combines with hydrogen ions to form water. Because O2 must be present for system to work, it is called oxidative phosphorylation.

38. We will continue with the Electron Transport system on Thursday as well a the Quiz for Chapter 9!We will continue with the Electron Transport system on Thursday as well a the Quiz for Chapter 9!

44. How Efficient is Aerobic Respiration? a. Glucose + O2 => CO2 + H2O 686 kcal (bomb calorimeter) b. ATP phosphate bond 7.3 kcal x 36 ATP = 263 kcal. c. Efficiency is 263/686 40% of available energy in glucose is transferred to ATP.

45. A bomb calorimeter can be used to measure the total energy for a food product. Calorimetry is a technique that is used to determine the heat involved in a chemical reaction. When determining the heat of combustion of a substance or the caloric value of foods, the measurements are often made using a bomb calorimeter. In this device, the weighed sample is placed in a heavy steel container called a bomb and the atmosphere of the bomb is filled with pure oxygen. The bomb is then placed in a well insulated container called a calorimeter which has been filled with a measured amount of water. The sample, in the pure oxygen atmosphere, is ignited by an electric spark and the heat generated by the burning sample warms the bomb and the surrounding water. At equilibrium, both the bomb and the water will be at the same temperature. Using the law of conservation of energy: Heat evolved by the reaction = Heat absorbed by the water + Heat absorbed by the bomb or, in equation form: qreaction = -(qwater + qbomb ) (where q is the symbol for heat) The qreaction has a negative value because the combustion reaction is exothermic (i.e., it releases energy to the surroundings). The qwater and the qbomb are calculated from the temperature change of the water and the bomb and the specific heat of the water and the bomb. The total gives the heat of combustion of the sample that was used. A bomb calorimeter can be used to measure the total energy for a food product.

47. Fermentation

48. Cellular Respiration Includes Fermentation Fermentation consists of glycolysis plus reduction of pyruvate to either lactate or alcohol and CO2. Occurs when oxygen is not readily available.

51. A. Cellular Respiration Includes Fermentation a. Anaerobic bacteria produce lactic acid when we manufacture some cheeses. b. Anaerobic bacteria produce industrial chemicals: isopropanol, acetic acid. c. Yeasts produce alcohol in winemaking. d. Animals reduce pyruvate to lactate when it is produced faster than it can be oxidized by Krebs cycle.

53. B. Advantages and Disadvantages of Fermentation 1. Despite low yield of two ATP molecules, fermentation provides quick burst of ATP energy for muscular activity. 2. Disadvantage is that lactate is toxic to cells. When blood cannot remove all lactate from muscles, lactate changes pH and causes muscles to fatigue.

54. C. How Efficient Is Fermentation? 1. Two ATP produced per glucose 14.6 kcal. 2. Complete glucose breakdown 686 kcal. of energy. 3. Efficiency for fermentation is 14.6/686 2 % - much less than complete breakdown of glucose.

57. Metabolism 1. Catabolism: Breaking Down 2. Anabolism: Building Up

59. B. Catabolism: Breaking Down 1. Glucose is broken down in cellular respiration 2. Fat breaks down into glycerol and three fatty acids. 3. Proteins (amino acids) break down into carbon chains and amino groups (urea).

61. B. Catabolism: Breaking Down b. An 18-carbon fatty acid is converted to nine acetyl-CoA molecules that enter the Krebs cycle. c. Respiration of fat products can produce 109 ATP molecules; fats are efficient form of stored energy.

62. Calories Fat contains 9 calories per gram Protein contains 4 calories/gram Carbohydrates has 5 calories per gram (approximately)

63. C. Anabolism: Building Up ATP produced during catabolism drives anabolism. Excess carbohydrates energy can result in fat synthesis.

64. C. Anabolism: Building Up Plants synthesize all amino acids they need; animals lack some enzymes needed to make some amino acids. Humans synthesize 11 of 20 amino acids; remaining 9 essential amino acids must be provided by diet.

65. The End.