1. Energy and Life

2. Energy = the ability to do work –Life on earth depends on a flow of energy –Cells need energy constantly to continue functioning.

3. Energy comes in many forms –Examples: Light Heat Energy stored in chemical compounds (like glucose)

4. Most cellular processes require the input of energy. Like what?

5. Examples: –Synthesis of new molecules proteins, enzymes, DNA etc. –Breakdown of molecules chemical digestion –Build new structures membranes, organelles, etc. –Maintain Homeostasis eliminate wastes, maintain body temp., active transport, cell movement etc.

6. Where do cells get this energy? –From food we eat –We measure the energy content of food in calories. –Certain reactions break down these molecules to release energy.

7. Energy released from a Gummy Bear http://www.youtube.com/watch?v=uj9D3m c7tVg&feature=related&safe=activehttp://www.youtube.com/watch?v=uj9D3m c7tVg&feature=related&safe=active

8. –Can’t use energy directly from food – Need to store it and release it gradually. –Store it in molecules of ATP.

9. ATP (Adenosine Triphosphate) –Source of cellular energy –Stores energy as food is broken down so that it can be released slowly to cell when needed rather than all at once. –A type of energy “currency”, that can be “paid out” as the cell needs it.

10. Structure of ATP (Adenosine triphosphate) –1 adenine (type of nitrogenous base) –1 ribose sugar (5 carbon ring) –3 phosphate groups

11. How is ATP Formed? –Energy is stored in high energy phosphate bonds

12. –Cells bond a third phosphate group to ADP –ADP (adenosine “di”phosphate)

14. –To release this energy again, the cell breaks off the 3 rd phosphate group and energy is released. –Can happen over and over again. –Like recharging a battery!

15. IMPORTANT TO KNOW!! How does ADP and ATP differ? How is this related to energy?

16. Storing Energy Add a phosphate to ADP ADP + phosphate + energy → ATP

17. Releasing Energy Remove a phosphate from ATP ATP → ADP + phosphate + energy Note: The enzyme that catalyzes this reaction is called ATPase.

18. Cells can regenerate ATP from ADP as needed by using the energy in foods like glucose.

19. ATP/ADP Cycle

20. How do organisms obtain food to make ATP?

21. They eat it… –Heterotrophs: obtain food from consuming other living things. Ex: –Animals: herbivores, carnivores and omnivores –Fungi –Some protists –Some bacteria

23. They make it themselves… –Autotrophs: use light energy from the sun to make their own food through photosynthesis. Ex: –Plants –Algae –Some bacteria

27. Photosynthesis Process by which light energy is converted into the chemical energy of organic compounds (glucose).

28. Occurs in the chloroplasts of plant cells (as wells as some single celled organisms, that can carry out photosynthesis.)

29. Chloroplast Structure Stroma: protein containing fluid Grana: stacked membranes containing enzymes and chlorophyll.

30. Chlorophyll: –green pigment necessary for photosynthesis. –Absorbs red and blue wavelengths of light and reflects green light. (that’s why most plants look green)

31. Note: –Other photosynthetic pigments exist besides chlorophyll, but it is the main one used by autotrophs Ex: Carotenoids (orange/red colored pigment)

32. Equation for Photosynthesis

33. Photosynthesis Overview Plants Take In: –Carbon Dioxide Gas –Water –Sunlight (energy) Plants Produce: –Glucose (form of stored energy) –Oxygen Gas

34. The Process of Photosynthesis How Does the Chloroplast Work? –Light Dependant Reactions (Photochemical) –Light Independent Reactions (Carbon Fixation)

35. Light Reactions Light Dependant Reactions (Photochemical) –Happen in the thylakoid membranes of grana –Directly involve chlorophyll and sunlight –Produces oxygen –Converts ADP to ATP –Converts NADP + to NADPH

36. Chlorophyll absorbs sunlight –Creates high energy electrons –Electrons enter the electron transport chain –Eventually produce some ATP

37. Photolysis –Water gets split inside grana Breaks into: –One oxygen atom –Two H + ions –2 electrons

38. The Oxygen produced by splitting water gets released into the air –Source of nearly all the oxygen in Earth’s atomosphere! Thank you plants!!! You make our lives possible.

39. The H+ ions and electrons –Join up with NADP + an “electron carrier” –It becomes NADPH

40. Making ATP H + ions build up and cross the thylakoid membrane causing ATP to form as ATP synthase (an enzyme) turns ADP into ATP

43. Dark Reactions Light Independent Reactions (Calvin Cycle) –Does not require light –Happens in stroma –Carbon Fixation: Carbon gets “Fixed” from a simple 1 carbon molecule (CO 2 ) to a complex 6 carbon one that holds stored energy (glucose/C 6 H 12 O 6 )

44. Carbon Dioxide Molecules: (CO 2 ) – enters from atmosphere (through stomata) –Combine to make PGAL a 3-carbon molecule –2 PGAL combine to produce a 6-carbon glucose –Energy for these reactions to take place is provided by ATP and NADPH (from light reactions)

47. Photosynthesis Summary

48. Light vs. Dark Reactions

49. Video Overview of Photosynthesis (5min) http://www.youtube.com/watch?v=mYbMP wmwx88&safe=activehttp://www.youtube.com/watch?v=mYbMP wmwx88&safe=active

50. Factors Affecting Photosynthesis –Temperature –Light Intensity –Water and Carbon Dioxide Availability Tutor Vista: http://www.youtube.com/watch?v=vmmWiJ3g9Cg&safe= active

51. Temperature: –Enzymes are needed for photosynthesis –Function best between 0°C and 35°C. –Too hot or too cold and photosynthesis stops

52. Intensity of Light: –More intensity = more photosynthesis –Remember blue and red wavelengths are most useful for photosynthesis

53. Availability of Water and CO 2 : –One of the raw materials for photosynthesis –Split during photolysis reaction –Water loss can kill plants –They have evolved strategies Waxy coatings on leaves

54. Stomata: –small openings in plant leaves that normally admit carbon dioxide –Water can also escape through opening Guard Cells: –Can open or close stomata to help prevent excess water loss from plant

55. Stomata and Guard Cells Video: http://www.youtube.com /watch?v=cFX4JrsPaUs &safe=active