HONORS BIOLOGY CHAPTER 6

1. HONORS BIOLOGY CHAPTER 6 Breaking Down Glucose

2. 6.1 • Ultimate source of energy • Photosynthesis and Cellular Respiration-how related?

3. Breathing and Cellular Respiration • Breathing: how our body inhales and exhales to take in oxygen and release carbon dioxide • Cellular Respiration: how our cells break down food sources (ie., glucose) to produce energy (ATP).

4. Respiration Really is... • Cellular respiration = breakdown of organic molecules (for energy) in the presence of oxygen (in mitochondrion)

5. 6.3 Cellular Respiration Equation Is this endergonic or exergonic?

6. Cellular Respiration Equation Is this endergonic or exergonic? Glucose breaks bonds and gives off energy (as seen on right side of the equation). ATP

7. Fill in the Blanks

9. 6.4 Energy Units • Kilocalories (kcal) • = Calories • = 1000 calories • = quantity of heat needed to raise 1 kg of water by 1oC

10. Daily Human Needs • 2,200 kcal of energy per day • Walking at 3 mph (burn 245 kcal/hour), how far would you have to travel to “burn off” the equivalent of a slice of pizza of about 475 kcal?

11. Daily Human Needs • 2,200 kcal of energy per day • Walking at 3 mph (burn 245 kcal/hour), how far would you have to travel to “burn off” the equivalent of a slice of pizza of about 475 kcal? • ~2 hours

12. 6.5 Where does the energy come from? • The bonds (electrons) with more energy (C6H12O6)and forming bonds with less energy (CO2 and H2O).

13. 6.3 Burn 1 glucose molecule with fire • ~ 100 ATP molecules • 100% energy released • BUT, in cells only about 34% goes to use in ATP molecules • The rest is lost as heat

14. 6.5 Cell’s Slow Burn • Cells tap energy from electrons “falling” gradually from organic fuels to oxygen. • This is slower and more controlled than just burning it with fire.

15. What drives this to happen? • OXYGEN • A strong tendency to pull electrons from other atoms • Oxygen is the “ultimate electron acceptor”

16. REVIEW: Catabolic Pathways • Metabolic pathways that release stored energy by breaking down complex molecules

17. To what molecule is the energy shuttled? • ATP • ADP to ATP animanimation

18. Oxidation loss of electrons from one substance Loss of H NADH NAD+ Reduction addition of electrons to another substance Gain of H NAD+ NADH “Redox reaction”Oxidation – Reduction Reaction

19. We don’t see e-, but we see H atoms. C6H12O6+ 6O2 6CO2+6H2O+ATP • (hydrogen atom = one proton and one electron)

20. We don’t see e-, but we see H atoms. C6H12O6+ 6O2 6CO2+6H2O+ATP • (hydrogen atom = one proton and one electron) LEO = loss of electrons = reduction

21. How to remember… • "Leo goes Ger” • Loss of electrons = oxidation • Gain of electrons = reduction

22. Fill in the Blanks: H+ 2H reduction NAD+ NADH oxidation becomes oxidized becomes reducedcarries 2 e-b

25. What is NAD+? • nicotinamide adenine dinucleotide • Coenzyme from vitamin niacin • used to shuttle electrons in redox reactions • Turns NAD+ into NADH

26. NAD+ to NADH

27. Electron Carrier • A.k.a. “hydrogen carrier” • Electron taxi cab (empty) NAD+ NADH (full with e-) e-

28. Lose electrons • C4H6O5 C4H2O5 • Oxidized Lose e- (H) • NAD+ NADH • Reduced Gain e- (H)

29. Which has more energy? • NAD+ or NADH? • Answer: NADH • What would the enzyme dehydrogenase do? • Strips two H from NADH

30. NAD+ NADH • Can NAD+ be recycled? • Yes • McGraw-Hill NAD+ Animation

31. Electron Transport Chain • Organic molecules with an abundance of C-H bonds are a source of e- with a potential to fall closer and closer to oxygen. • An e- loses its potential when it shifts from a less electronegative atom (doesn’t attract e- as much) to a more electronegative atom (attracts e- more).

32. ETC Animation of Energy Release from an Electron Transport System • Electron Transport Chain • Electrons are passed from the hydrogen carrier NADH to oxygen from one molecule to another

33. What keeps… • The electrons moving down the chain? • Each e- carrier molecule has greater affinity for e- than its uphill neighbor • Electron Transport System and ATP Synthesis (little movie) • Krebstca (animation)

34. Where are ETC’s found? • In membranes of: • Mitochondria • Chloroplasts

35. Everything you wanted to know about the Mitochondrion • Mitochondrion Animation • Note many folds (cristae) of inner membrane • This increases surface area

36. Mitochondrion Matrix contains mDNA (mitochondrial), enzymes, and ribosomes-site of Krebs cycle

37. 6.6 3 Stages of Cellular Respiration: • 1. Glycolysis- occurs in cytoplasm • Glucose 2 mols. of pyruvate • 2. Pyruvate oxidation and citric acid cycle -occurs in mitochondrion • Pyruvate Acetyl CoA CO2 + NADH • 3. Oxidative phosphorylation-in mitochondrion uses ETC and chemiosmosis in mitochondrion to make lots of ATP

38. Cellular Respiration • Cellular respiration converts the potential energy of glucose into usable energy of ATP. • THERE ARE 2 WAYS THE ATP IS GENERATED. • 

39. 2 Ways to Make ATP • Substrate-Level Phosphorylation • (without a membrane; it occurs in the cytoplasm or matrix of mitochondrion with help of an enzyme) • Oxidative Phosphorylation • diffusion of particles through a membrane produces ATP

40. Substrate-Level Phosphorylation • Use of enzymes (not membranes) to join P to ADP to make ATP

41. Oxidative Phosphorylation • Uses a membrane (of mitochondrion or chloroplast) to pass electrons down the electron transport train to a final electron acceptor.

42. 6.7 GLYCOLYSIS • A. Energy Investment Phase • Glucose is phosphorylated into 2 molecules of G3P • Uses 2 ATP

45. GLYCOLYSIS • B. Energy Payoff Phase • 2 G3P break down to 2 pyruvates • Two NAD+ add 2 electrons 2 NADH + 2H+ -4 ATP form, net gain of 2 ATP

47. Glycolysis • Start with 6-carbon glucose and breaks into two 3-carbon pyruvic acid molecules (or pyruvate) • glucose + 2 NAD+ + 2 ADP + 2 Pi2 pyruvate + 2 NADH + 2 ATP

48. Glycolysis actually has 9 steps…but you only need to learn that these molecules formed between glucose and pyruvic acid are called intermediates

49. One Intermediate • G3P • = PGAL • = Glyceraldehyde 3-phosphate • =Phosphoglyceraldehyde

50. Needs 2 ATP to get started Makes 4 ATP Net Gain of 2 ATP Splits glucose into 2 pyruvates Makes NADH NET GAIN2 ATP’s Glycolysis Animation (nice big carbons) Glycolysis: What do I need to know?