1. Cells and Energy Chapter 4 Mr. Scott

2. Energy and Life Energy Energy –The ability to do work –Without the ability to obtain and use energy, life would cease to exist

3. Energy and Life Autotrophs Autotrophs –Organisms that make their own food  Plants –Plants and some other types of organisms are able to use light energy from the sun to produce food

4. Energy and Life Heterotrophs Heterotrophs –Organisms that obtain energy from the food’s they consume  Ex. Animals –Animals and some other organisms cannot use the sun’s energy directly  Some eat autotrophs  Some eat other animals  Some decompose other organisms

5. Energy and Life Chemical energy and ATP Chemical energy and ATP – ATP - Adenosine Triphosphate  One of the principle chemical compounds that cells use to store and release energy  Consists of adenine, ribose, and 3 phosphate groups

6. Energy and Life –Storing Energy  ADP –Adenosine diphosphate –Two phosphates instead of three phosphates –Adding a phosphate to ADP produces ATP  ADP  ATP

7. Energy and Life –Releasing Energy  The characteristics of ATP make it exceptionally useful as the basic energy source of all cells  ATP  ADP

8. Energy and Life Uses Biochemical Energy Uses Biochemical Energy –Active Transport  Sodium-potassium pump –Pumps sodium out of and potassium into the cell –Cellular movement –Organelle functioning  Organelle movement within the cell –Storage  ATP is not good at storing energy  Glucose is better than ATP for long term storage  90 times more energy

9. Photosynthesis Investigating Photosynthesis Investigating Photosynthesis –Photosynthesis  Plants use the sunlight to convert water and carbon dioxide into carbohydrates and oxygen

10. Photosynthesis –Van Helmont’s Experiment  Where does the mass of a tree come from?  The mass comes from the water –Soils mass was nearly unchanged –Water was the only thing added –Other things were not taken into consideration by Van Helmont

11. Photosynthesis –Priestly’s Experiment  Lit candle in a jar experiment –Flame gradually went out  Something in the air allowed the candle to burn  What was this substance?

12. Photosynthesis –Priestly – Part 2  He placed a mint leaf in one jar and the candle in another  Mint plant allowed the flame to last much longer  Mint plant produced something that the candle flame required  What was this substance?

13. Photosynthesis –Jan Ingenhousz Experiment  Lit candle in a jar with mint plant and no light –Flame did not last as long as with mint plant in light –What does this demonstrate?  Light is necessary for plants to produce oxygen!

14. Photosynthesis Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high-energy sugars and oxygen Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high-energy sugars and oxygen

15. Photosynthesis Photosynthesis Equation Photosynthesis Equation –6CO 2 + 6H 2 O + (light)  C 6 H 12 O 6 + 6O 2 –Carbon Dioxide + Water (with light)  Sugars + Oxygen

16. Photosynthesis Light and Pigment Light and Pigment –The equation tells you what is needed, BUT not what happens –Photosynthesis requires light and a substance called chlorophyll  Found in chloroplasts  Makes plants look green

17. Photosynthesis –Sun’s energy travels to Earth as light  Pigments are molecules that absorb light  Chlorophyll is the main pigment in plants –Why are plants green? –Plants absorb all of the light spectrum except for green –The light that is absorbed is converted to energy in the electrons of the chlorophyll

18. Photosynthesis Two different types of chlorophyll Two different types of chlorophyll –Chlorophyll α –Chlorophyll β Not all plants are green…How? Not all plants are green…How? –Some plants contain red or orange (carotene) that make them different colors

19. The Reactions of Photosynthesis Inside a Chloroplast Inside a Chloroplast –The organelle where photosynthesis takes place  Thylakoid –Saclike photosynthetic membranes  Grana (Granum) –Stacks of thylakoids  Photosystems –Clusters of pigment and protein that absorb light energy  Stroma –Area outside of the thylakoid in the chloroplast

20. The Reactions of Photosynthesis

21. Electron Carriers Electron Carriers –Electron Transport Chain  Transports the electrons between photosystems –Transport high-energy electrons to other molecules  Electrons gain energy from sunlight  These electrons exist inside the chlorophyll  Something has to be done with these electrons

22. The Reactions of Photosynthesis –NADP+  Chloroplasts trap energy from the sun  Two electrons and a hydrogen molecule make NADPH  NADPH can move to other parts of the cell and make things like glucose

23. The Reactions of Photosynthesis Light-Dependent Reactions Light-Dependent Reactions –Produce oxygen gas and convert ADP and NADP + into the energy carriers ATP and NADPH

24. The Reactions of Photosynthesis –Photosystem II pigments absorbs light  Light absorbance excites electrons to a higher energy level  High-energy electrons move to the electron transport chain  Thylakoid replaces lost electrons from stored water – Two hydrogen molecules (New Electrons) – One oxygen (Waste)

25. The Reactions of Photosynthesis –High-energy electrons move from photosystem II to photosystem I  Energy from the electrons is used to move hydrogen ions from the stroma to the inner thylakoid space

26. The Reactions of Photosynthesis –Photosystem I uses light to reenergize the electrons  NADP + picks up the high-energy electrons and hydrogen ions to make NADPH

27. The Reactions of Photosynthesis –Hydrogen ions are pumped across the thylakoid membrane  This happens until the inside of the thylakoid is positive and the outside is negative  This results in energy that can be used to make ATP –the useable form of energy for the plant cell!

28. The Reactions of Photosynthesis –Hydrogen ions cannot pass through the thylakoid membrane directly –ATP synthase – membrane protein –Allows hydrogen to pass through –ATP synthase will bind ADP and phosphate  ATP

29. The Reactions of Photosynthesis Summary of light reactions: Summary of light reactions: –Water breaks down - hydrogen ions and oxygen –NADP+ becomes NADPH – electrons and hydrogen ions to photosystem I –ADP to ATP via ATP synthase –YEAH!!! We have ATP, now what?

30. The Reactions of Photosynthesis Calvin Cycle Calvin Cycle –Uses ATP and NADPH from the light dependent reactions to produce high-energy sugars –Does NOT require light to proceed – it uses the energy captured from the light reactions. –This is where carbon dioxide (CO 2 ) is used.

31. The Reactions of Photosynthesis Factors affecting photosynthesis Factors affecting photosynthesis –H 2 O  Plants require water for photosynthesis to occur  Dry conditions - waxy covering –Temperature  Enzymes require temperature range of 0 o – 35 o C –Light Intensity  The more light the more photosynthesis to a point

32. Cellular Respiration Chemical Energy and Food Chemical Energy and Food –calorie (c)  The amount of energy needed to raise the temperature of 1 gram of water 1 o C  Calorie (C) is equal to 1000 calories (kilocalorie) –This is the one on food labels

33. Cellular Respiration Cellular Respiration Cellular Respiration –Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.  Cellular respiration - If oxygen is present for glycolysis then Krebs cycle and the electron transport chain come after –6O 2 + C 6 H 12 O 6  6CO 2 + 6H 2 O + Energy

34. Cellular Respiration Glycolysis Glycolysis –The process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3- carbon compound

35. Cellular Respiration – ATP Production  2 ATP molecules are used in the production  4 ATP molecules are produced  2 ATP molecules are gained or there is a 2 net gain

36. Cellular Respiration –NADH Production  Removes 4 high- energy electrons and passes them to NAD +  NADH is made and will hold the electrons to be transferred to other molecules  Glycolysis cannot continue this process forever without oxygen

37. Cellular Respiration Fermentation Fermentation –Process that releases energy from food molecules by making ATP without oxygen.  Anaerobic –Process that does NOT require oxygen

38. Cellular Respiration –Alcoholic Fermentation  pyruvic acid + NADH  alcohol + CO 2 + NAD + –Yeast in the bread dough causes this process to make bread rise

39. Cellular Respiration –Lactic Acid Fermentation  pyruvic acid + NADH  lactic acid + NAD + –This is why your muscles burn –This process is used to make cheese, yogurt, buttermilk, and sour cream

40. Krebs and Electron Support Krebs and electron transport Krebs and electron transport After glycolysis After glycolysis –90% of total energy is still unused  Aerobic – Require oxygen

41. Krebs and Electron Support Krebs Cycle Krebs Cycle –Also called the citric acid cycle –Pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions

42. Krebs and Electron Support – Citric acid production  Pyruvic acid comes into the mitochondrion  One carbon breaks off  The other two carbons combine with coenzyme A forming Acetyl-CoA  Acetyl-CoA combines with a 4-carbon molecule to make citric acid

43. Krebs and Electron Support –Energy extraction  Citric acid is broken down and electrons are transferred to electron carriers –One carbon is removed, then another carbon  Making CO 2  This is why you exhale CO 2 –ATP is produced  It is used for cell activities –NAD + and FAD  Convert to NADH and FADH 2  Can produce large amounts of ATP

44. Krebs and Electron Support Electron Transport Electron Transport –The electron transport chain uses high-energy electrons from the Krebs cycle to convert ADP into ATP

45. Krebs and Electron Support –Electron transport  High-energy electrons are transferred from NADH and FADH 2 to the electron transport chain  These electrons connect to hydrogen and oxygen to make water

46. Krebs and Electron Support –Hydrogen ion movement  Two high-energy electrons cause a H + to move across the cell membrane  This makes the inside of the mitochondria positively charged –ATP production  H + ions leave the mitochondria causing the ATP synthase to spin making one ATP from one ADP for each rotation

47. Krebs and Electron Support The Totals The Totals –Glycolysis  2 ATP/Glucose molecule –Krebs cycle and Electron transport chain  34 ATP/Glucose molecule –Total  36 ATP/Glucose  38% of total energy of glucose

48. Krebs and Electron Support Energy and Exercise Energy and Exercise –Quick energy  Use of stored ATP  Lasts for up to 90 seconds  Lactic acid is produced

49. Krebs and Electron Support –Long-term energy  Cellular respiration  Energy is produced for a longer period of time –Glycogen –Lasts for 15 to 20 minutes