1. Cell Energy & Photosynthesis

2. Source of Energy In most living organisms the energy in most food comes from? the sun autotroph – ‘auto’ – self, ‘troph’ – food. organisms which are able to make their own food –examples? Cell Energy

3. Source of Energy heterotroph –‘heteros’– other,‘troph’– food. obtain energy from the foods they eat. –Impalas ? –Leopards ? –Mushrooms ? to live, all organisms must release the energy stored in sugars and other compounds Cell Energy

4. Source of Energy In nature there are many forms that energy can take examples? –heat –light –nuclear –kinetic – motion –electrical –and chemical Cell Energy

5. Stored Energy One of the principal chemical compounds that living things use to store energy is? adenosine triphosphate (ATP) an ATP molecule consists of the following –a nitrogen-containing compound - adenine Cell Energy

6. Adenine Cell Energy adenosine tri-phosphate (ATP)

7. Stored Energy One of the principal chemical compounds that living things use to store energy is? adenosine triphosphate (ATP) an ATP molecule consists of the following –a nitrogen-containing compound – adenine –a 5-carbon sugar - ribose Cell Energy

8. adenosine tri-phosphate (ATP) Adenine Ribose Cell Energy

9. Stored Energy One of the principal chemical compounds that living things use to store energy is? adenosine triphosphate (ATP) an ATP molecule consists of the following –a nitrogen-containing compound – adenine –a 5-carbon sugar – ribose –and 3 phosphate groups Cell Energy

10. Adenine Ribose3 Phosphate groups Cell Energy adenosine tri-phosphate (ATP)

11. Stored Energy adenosine diphosphate (ADP) has a structure similar to ATP but with one important difference –ADP has 2 phosphate groups instead of 3 the addition of that 3 rd phosphate group allows the cell to store small amounts of energy similar to a battery storing energy Cell Energy

12. ATP – stored energy Adenosine Diphosphate (ADP) + phosphate Cell Energy

13. Adenosine Diphosphate (ADP) + phosphate Partially charged battery ATP – stored energy Cell Energy

14. Adenosine Diphosphate (ADP) + phosphate Partially charged battery energy ATP – stored energy Cell Energy

15. ATP – stored energy Adenosine Diphosphate (ADP) + phosphate Partially charged battery Adenosine triphosphate (ATP) energy Cell Energy

16. ATP – stored energy Adenosine Diphosphate (ADP) + phosphate Partially charged battery Adenosine triphosphate (ATP) Fully charged battery energy Cell Energy

17. Releasing energy from ATP the energy stored in ATP is released when ATP is converted to ADP and a phosphate group. –this adding and subtracting of a third phosphate group is a way of a cell storing and releasing energy as needed Cell Energy

18. Is there another molecule similar to ATP & ADP? AMP

19. Releasing energy from ATP the ATP molecule carries just enough energy to power a variety of cellular activities active transport – sodium-potassium pump. enough energy to transport 3 sodium ions and 2 potassium ions move organelles along microtubules inside cell Cell Energy

20. ATP-ADP cycle Cell Energy

21. ATP and Glucose most cells have only a small amount of ATP – enough to last for a few seconds of activity. –why? ATP is very efficient at transferring energy but not very good at storing large amounts of energy what can store lots of energy for a cell? Cell Energy

22. ATP and Glucose glucose – stores more than 90 times the chemical energy of a molecule of ATP cells can therefore use carbohydrates like glucose to regenerate ATP from ADP Cell Energy

23. Photosynthesis Equation light 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 carbon dioxide + water sugar + oxygen Cell Energy

24. Light and Pigments In addition to water and carbon dioxide, photosynthesis requires? light &? chlorophyll, a molecule in chloroplasts Cell Energy

25. Light and Pigments energy from the sun travels to the Earth in many forms. one of these forms is light (sunlight) which your eyes perceive as ‘white light’ –it is actually a mixture of different wavelengths of light –many of these wavelengths are visible to your eyes and are referred to as the visible spectrum –R O Y G B I V Cell Energy

26. Light and Pigments plants gather the sun’s energy with light- absorbing molecules called pigments the plants principal pigment is chlorophyll –there are 2 main types of chlorophyll chlorophyll a and chlorophyll b Cell Energy

27. Absorption of light by chlorophyll a and chlorophyll b chlorophyll b chlorophyll a chlorophyll absorbs light very well in the blue and red regions however, it does not absorb it very well in the green and yellow regions Cell Energy

28. Light and Pigments light is a form of energy, any compound that absorbs light also absorbs the energy from that light. when chlorophyll absorbs light much of the energy is transferred directly to electrons in the chlorophyll molecules, raising the energy levels of these electrons these high energy electrons make photosynthesis work Cell Energy

29. Inside a Chloroplast thylakoid membranes –saclike photosynthetic membranes –contain clusters of chlorophyll and other pigments and proteins known as photosystems –able to capture the energy of sunlight grana – (singular: granum) stacks of thylakoids stroma – fluid region outside the thylakoid membranes Cell Energy

30. Photosynthesis light-dependent reactions –occurs in the __________ _________ Cell Energy

31. Photosynthesis light-dependent reactions –occurs in the thylakoid membranes Cell Energy

32. Chloroplast light- dependent reactions Photosynthesis Cell Energy

33. Photosynthesis light-dependent reactions –occurs in the thylakoid membranes –requires – ? Cell Energy

34. Photosynthesis light-dependent reactions –occurs in the thylakoid membranes –requires – light energy, water & raw materials Cell Energy

35. Chloroplast light- dependent reactions light H2OH2O raw materials Photosynthesis Cell Energy

36. Photosynthesis light-dependent reactions –occurs in the thylakoid membranes –requires – light energy, water & raw materials –produces – ? Cell Energy

37. Photosynthesis light-dependent reactions –occurs in the thylakoid membranes –requires – light energy, water & raw materials –produces – oxygen, ATP & NADPH Cell Energy

38. Chloroplast light- dependent reactions light H2OH2O O2O2 ATP NADPH Photosynthesis Cell Energy

39. Photosynthesis light-independent reactions –also referred to as the ? Calvin cycle –occurs in the ? stroma Cell Energy

40. Chloroplast light- dependent reactions light H2OH2O O2O2 ATP NADPH Calvin Cycle Photosynthesis Cell Energy

41. Photosynthesis light-independent reactions –also referred to as the ? Calvin cycle –occurs in the ? stroma –requires? carbon dioxide, ATP & NADPH Cell Energy

42. Chloroplast light- dependent reactions light H2OH2O O2O2 ATP NADPH Calvin Cycle CO 2 Photosynthesis Cell Energy

43. Photosynthesis light-independent reactions –also referred to as the ? Calvin cycle –occurs in the ? stroma –requires? carbon dioxide, ATP & NADPH –produces? sugars, NADP +, & ADP + P Cell Energy

44. Chloroplast light- dependent reactions light H2OH2O O2O2 ATP NADPH Calvin Cycle CO 2 sugars ADP + P NADP + Photosynthesis Cell Energy

45. NADPH when sunlight excites electrons in chlorophyll, the electrons gain a great deal of energy a special carrier is needed to move these high-energy electrons –similar to hot coals of a fire Cell Energy

46. NADPH carrier molecule –compound that can accept a pair of high- energy electrons and transfer them along with most of their energy to another molecule Cell Energy

47. NADPH NADP + - carrier molecule that accepts and holds 2 high-energy electrons along with a hydrogen ion (H + ) –results in the production of NADPH –this conversion to NADPH allows some energy of light to be trapped in a chemical form –chemical energy can then be used by cell for chemical reactions elsewhere in cell Cell Energy

48. Light-Dependent Reactions Step A – Photosystem II –pigments in photosystem II absorb light via antenna complexes –energy from light is absorbed by electrons – increasing their energy level –energy is then passed on to the electron transport chain –enzymes break up water molecules into electrons, hydrogen ions (H + ), and oxygen Cell Energy

49. Stroma inner thylakoid membrane thylakoid membrane Cell Energy Light-Dependent Reactions

50. Step B – Electron transport chain (ETC) –high-energy electrons move through electron transport chain –energy from electrons is used by molecules to transport H + ions from stroma to the inner thylakoid Cell Energy

51. Stroma inner thylakoid membrane thylakoid membrane Cell Energy Light-Dependent Reactions

52. Step C – Photosystem I –Pigments in photosystem I use light energy to reenergize the electrons –NADP + picks up these high-energy electrons plus a H + ion and becomes NADPH Cell Energy

53. Stroma inner thylakoid membrane thylakoid membrane Cell Energy Light-Dependent Reactions

54. Step D – Hydrogen Ion movement –H + ions released during water-splitting and electron transport result in a slight positive charge inside the thylakoid membrane and a slight negative charge outside Cell Energy

55. Stroma inner thylakoid membrane thylakoid membrane Cell Energy Light-Dependent Reactions

56. Step D – Hydrogen Ion movement –H + ions cannot cross the membrane directly –membrane contains a protein called ATP synthase that allows H + ions to pass through it –as H + ions pass through the protein, the protein rotates like a turbine –as it turns, ATP synthase binds ADP and a phosphate group to form ATP Cell Energy

57. Stroma inner thylakoid membrane thylakoid membrane Cell Energy Light-Dependent Reactions

58. Z – scheme: PII & PIZ – scheme

59. The Calvin Cycle Step A – CO 2 enter the cycle –six CO 2 molecules enter cycle from atmosphere –they combine with six 5-carbon molecules –the end result is twelve 3-carbon molecules Cell Energy

60. The Calvin Cycle

61. Step B – Energy input –the twelve 3-carbon molecules are converted into higher-energy forms –energy for this conversion comes from ATP and high-energy electrons of NADPH Cell Energy

62. The Calvin Cycle

63. Step C – 6-carbon sugar produced –two of the twelve 3-carbon molecules are converted into two similar 3-carbon molecules –These molecules are used to form various 6-carbon sugars and other compounds Cell Energy

64. The Calvin Cycle

65. Step D – 5-carbon molecules regenerated –The remaining ten 3-carbon molecules are converted back into six 5-carbon molecules –These molecules combine with six new CO 2 molecules to begin the next cycle Cell Energy

66. The Calvin Cycle

67. Factors affecting photosynthesis water –because it is a raw material, a shortage can slow or stop process temperature –enzymes used in process work best between 0 o C and 35 o C. Temps above or below range may damage enzymes and slow down process intensity of light –increasing intensity also increases rate of photosynthesis up to a certain point Cell Energy