Biology 20

1. Biology 20 Photosynthesis, Cellular Respiration

2. ATP • WHAT IS ATP? • Universal Energy Molecule • Energy in a form the cell can use • Makes energy readily available • Continuously being remade • Stands for Adenosine Triphosphate P P + P Adenosine

3. WHAT IS ATP? Universal Energy Molecule Makes energy readily available Continuously being remade Stands for Adenosine Triphosphate P P + P P P P High Energy Bond ATP Adenosine Adenosine

4. ATP • What is ATP used for? 1.Motion 2. Transport of ions and molecules. 3. Building molecules 4. Switching reactions on or off

5. Electron Transfer • The transfer of electrons is important in ATP production. • Electron carriers • strip a hydrogen proton and its electron from a number of organic compounds • Respiration • NAD+(becomes NADH) • Photosynthesis • NADP+ (becomes NADPH)

6. Biology 20 Photosynthesis

7. Introduction • Photosynthesis is… • the process by which plants and some bacteria use chlorophyll, a green pigment, to trap sunlight energy. • The energy is used to synthesize carbohydrates Solar Energy Chemical Bond Energy of Carbohydrates Converted

8. Chlorophyll • A green chemical which traps sunlight energy • Located in the chloroplast

9. Chloroplast Parts • Thylakoid • Disk • Granum = stack of disks • Grana = many stacks • site of light dependent reaction • Stroma • gel surrounding the thylakoids • site of light independent reaction

10. Plant Cell Thylakoid Location Chloroplast Thylakoid Stacks Thylakoid

11. Leaves in the fall • Why do leaves change colors in the fall?

12. Pigments • White light is composed of all colors • red, orange, yellow, green, blue, indigo, violet • Chlorophyll • reflects green light • absorbs blue and red ends of the spectrum • chlorophyll a -- blue green • chlorophyll b -- green • Other pigments absorb light energy from other parts of the spectrum. Carotenoids (orange) Xanthophyll (yellow)

13. Leaves in the fall • Because of light. • A decrease in light intensity and length. • Causes the chlorophyll molecule to break down, exposing the other pigments

14. General Equation • There are two steps in photosynthesis • Light Dependent Reaction • Light Independent Reaction (no light required) C H O + 6O 6 CO + 6 H O 2 2 2 6 12 6

15. Light Dependent Reaction Light Independent Reaction General Outline Water Light Energy Carbon Dioxide ATP NADPH Sugar Oxygen

17. Explain how glucose is oxidized during Glycolysis and the Krebs Cycle to produce reducing power in NADH and FADH • Describe where in the cell this takes place • Explain how chemiosmosis converts the reducing power of NADH and FADH to store chemical potential energy as ATP • Describe where in the mitochondrion this takes place Cellular Respiration

18. Cellular Respiration • Photosynthesis – stores energy • Cell Respiration – releases energy + 6 + 6 = + 6 Sunlight Energy H2O Glucose O2 CO2 Photosynthesis

19. Cellular Respiration • Photosynthesis – stores energy • Cell Respiration – releases energy + 6 + 6  + 6 H2O Glucose Sunlight Energy CO2 O2 Photosynthesis Chemical Energy + 6 + Glucose O2  6 + 6 CO2 H2O Cellular Respiration!

20. Notice that the wastes from photosynthesis are used as raw materials in cellular respiration • Atmospheric CO2 and water are used in photosynthesis, while Oxygen is released. • Atmospheric oxygen is used during Cellular respiration, while CO2 and water is released.

21. General Information • Cellular respiration the process by which cells break down glucose into carbon dioxide and water, releasing energy • You can think of respiration as the combustion of gasses in a car’s engine.

22. Car’s Engine • MAIN ENGINE = Mitochondrion – The site of the majority of ATP synthesis • MAIN FUEL = Glucose – fats and proteins may also be used in some instances • MAIN EXHAUST = CO2 and H2O.

23. The 4 Steps of Cellular Respiration • Glycolysis • Pyruvate Oxidation 3. Krebs Cycle 4. Electron Transport Chain

24. 1. Glycolysis (in cytoplasm) Glucose 2 ATP 2 ADP 2 ADP 2 ADP 2 ATP 2 ATP + NAD + NAD NADH NADH Pyruvic Acid Pyruvic Acid

25. Mitochondria • mitochondrial matrix the fluid that fills the interior space of the mitochondrion

26. 2. Pyruvate Oxidation • After glycolysis, if there is oxygen available, the pyruvate molecules are changed so the Krebs cycle can use them. • CO2 portion is removed and released as waste product • An electron is released to NAD+  NADH • Pyruvate Acetyl-CoA

27. 3. Krebs Cycle • Discovered by Sir Hans Kreb in 1937 • The Krebs cycle is an eight-step process • Key features of the Krebs Cycle • During one complete cycle a total of three NAD+ and one FAD are reduced to form three NADH and one FADH • During one complete cycle one ATP is formed • During one complete cycle three CO2 molecules are produced • However since glycolysis provides 2 pyruvate molecules, we double all our numbers!

28. Krebs Cycle 2 ADP 2P 2 ATP 2 Acetyl CoA 4 Carbon Dioxide 6 NADH 6 NAD 2 FADH 2 FAD

30. 4. Electron Transport Chain • Electron Transport Chain • Occurs on the inner membrane of the mitochondrion • Involves a group of molecules built into the inner membrane of the mitochondrion • Electrons pulled off of food by Glycolysis and Krebs are passed between these molecules. • This will ultimately result in the production of ATP • Oxygen is required for this step. • Lots of ATP is made (32)

31. Mitochondria

32. Electron Transport Chain Intermembrane Space Inner Membrane Matrix

33. High Energy Electron + H Intermembrane Space + H Electron H H Inner Membrane Cytochromes H H Low Energy Electron Matrix NADH

34. So Where Did All The Energy Go??

35. + H Intermembrane Space + + + + H H H H + + + H H H + + Inner Membrane + H H H + + + H H H + H + + + H H H + + + H H H Matrix ADP ATP P + + H + + + H H H H

36. + H Intermembrane Space + + + + H H H H + + + H H H + + Inner Membrane + H H H + + + H H H + H Oxygen + + + H H H + + + H H H Matrix ADP ATP P H O 2 + + H + + + H H H H

37. For each NADH that enters the Electron Transport Chain, how many ATP are produced?

38. For Each NADH Entering the ETC, 3 ATP Are Produced! But What About FADH?

39. Each FADH is only able to produce 2 ATP in the ETC

40. chemiosmosis a process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme

43. Oxygen is the final electron acceptor. If there is no oxygen, the electron transport chain gets “backed up” as there is no where for the electrons to go. NADH NAD+ As a result, Krebs stops due to lack of NAD+ Lack of NAD+ also causes [H+] to increase The body’s pH begins to fall inhibiting normal enzyme activity. What’s Up With Oxygen?

44. Review • Explain how glucose is oxidized during Glycolysis and the Krebs Cycle to produce reducing power in NADH and FADH • Describe where in the cell this takes place • Explain how chemiosmosis converts the reducing power of NADH and FADH to store chemical potential energy as ATP • Describe where in the mitochondrion this takes place

45. Let’s revisit Glycolysis! • Glycolysis created two molecules of pyruvate • Oxygen available  aerobic respiration occurs (Krebs, ETC) • No oxygen  anaerobic respiration

46. Anaerobic Respiration • Since pyruvic acid is poisonous, it must be converted into a safer form. • In animals (muscles!) -- LACTIC ACID • causes muscle cramps • process is called Lactic Acid Fermentation

47. Anaerobic Respiration • In bacteria and yeast -- ETHYL ALCOHOL & CO2 • process is called Alcohol Fermentation Both only Yield 2 ATP! Very inefficient!

48. Photosynthesis Energy required Oxygen released CO2 and H20 required Glucose produced Respiration Energy Produced Oxygen required CO2 and H20 produced Glucose required Comparison of Photosynthesis and Respiration