1. Energy in a Cell The Need for Energy

2. Cell Energy Autotrophs – make their own food Heterotrophs must get energy from consuming other organisms

3. Autotrophs – such as plants, make food from light energy Light energy is transformed into chemical energy as chemical bonds

4.  All chemical bonds store energy, some more than others

5.  There is a LOT of energy in a carbon to carbon bond (these are in organic molecules such as sugar)  There is too much energy in a carbon-carbon bond for normal cell processes

6.  So…mitochondria break down organic compounds, like sugars and fats, and convert the energy into ATP or adenosine triphosphate

7. ATP  Composed of:  Adenine – amino acid  Ribose – 5-carbon sugar  3 phosphate groups  The phosphate groups are charged particles

8. ATP  It requires a lot of energy to force the phosphate groups to bond because of their same charges  All that energy becomes available when the bonds are broken between the phosphates

9. ATP  When ATP has the last phosphate broken off to release the energy, it becomes ADP (adenosine diphosphate)

11. Photosynthesis Trapping the Sun’s Energy

12. The Photosynthesis Equation  Word equation:  Carbon dioxide + water light > glucose + oxygen  Chemical equation:  6 CO 2 + 6 H 2 O light > C 6 H 12 O 6 + 6 O 2

13. Light and Pigments  Photosynthesis requires light-catching pigments  Chlorophyll  Accessory pigments include: xanthophyll and beta carotine

14. Reactions in the Chloroplast  Thylakoids – membrane sacs that contain clusters of pigment molecules called photosystems  Grana- stacks of thylakoids  Stroma – area outside the thylakoid

15.  Light dependent reactions happen in the thylakoids (that’s where the light- catching pigments are)  Light independent reactions happen in the stroma

18. NADPH  The process of capturing sunlight results in the formation of high energy electrons  These high energy electrons require special carrier molecules

19. NADPH NADP + is a carrier molecule. NADP + is a carrier molecule. - nicotinamide adenine dinucleotide phosphate - accepts a pair of high energy electrons along with a hydrogen ion: H +- accepts a pair of high energy electrons along with a hydrogen ion: H + - creates NADPH

20. Light Dependent Reactions  Requires Light  Turns ADP and NADP + into the high energy carriers ATP and NADPH

21. How does it work?  Light is first absorbed by pigments in Photosystem II  Absorbed light increases energy in electrons which are passed to electron transport chain  New electrons for chlorophyll come from water

22.  High energy electrons travel from Photosystem II to Photosystem I on the Electron Transport Chain  Electron Transport Chain drives transport H + across the membrane of the thylakoid

23.  Photosystem I reenergizes high energy electrons and transfers them to NADP + which becomes NADPH after picking up H +  Process creates a charge difference across the thylakoid membranes; restoring the charge balance drives ATP creation

24.  H + concentration is higher on one side of the thylakoid membrane than the other  Facilitated diffusion happens to correct charge imbalance

25.  ATP synthase helps with facilitated diffusion of hydrogen ions, but uses their passage to create ATP  Drives ATP synthesis

27. The Calvin Cycle  ATP and NADPH are not stable enough to store energy for long  The Calvin Cycle converts less stable, high energy molecules into high energy sugars (glucose)  Calvin Cycle is light- independent

28. How Does it Work?  6 carbon dioxide molecules combine with 6 5-carbon molecules  combine with six 5-carbon molecules which split creating twelve 3 carbon molecules

29.  3 carbon molecules are then converted to high energy form using the energy from ATP and NADPH  2 of the twelve 3-carbon compounds are converted to similar molecules and combined to form a 6-carbon sugar

30.  The remaining ten 3-carbon compounds are recombined into 5-carbon compounds and re- enter the cycle  Plants use 6-carbon sugars for energy for growth and repair, and to construct complex carbohydrates like cellulose

33. Chap 9.2: Photosynthesis (summary)  Photosynthesis happens in 2 stages; light-dependant reactions, and light-independent reactions in the chloroplast.  Light-dependant reactions - energy is passed down the electron- transport chain to form ATP

34.  Photolysis of water releases O 2 and restores electrons for electron transport chain. NADPH forms for use in light-independent rxs.  Light-independent reactions (Calvin Cycle) uses CO 2 to form sugar in the stroma of the chloroplast.

35. Cellular Respiration

36. Chapter 9.3: Big Ideas  Cellular Respiration happens in 3 stages:  glycolysis,  the citric acid cycle(Krebs cycle),  the electron transport chain.

37. Chapter 9.3: Big Ideas (cont)  Glycolysis- breaks down glucose to make pyruvic acid and ATP to start the respiration process.

38. Chapter 9.3: Big Ideas (cont)  Citric Acid cycle- breaks down Acetyl-CoA and forms ATP and CO2 in the Mitchondria  Electron Transport Chain- Produces ATP and H2O

39. Cellular Resp. Overview Process used by cells to release energy from foods using oxygenProcess used by cells to release energy from foods using oxygen oxygen + glucose  carbon dioxide + water + energyoxygen + glucose  carbon dioxide + water + energy

40. Cellular Resp. Overview (cont) 6 O 2 + C 6 H 12 O 6  6 CO 2 + 6 H 2 O + Energy6 O 2 + C 6 H 12 O 6  6 CO 2 + 6 H 2 O + Energy Involves glycolysis and the Krebs or Citric Acid CycleInvolves glycolysis and the Krebs or Citric Acid Cycle

41. Glycolysis  Basically: one glucose (6- carbon sugar) is split into 2 pyruvic acid (3-carbon molecules)  2 ATP are needed to start process, but 4 ATP are produced

42. Glycolysis (cont)  NAD + is another high energy electron pair acceptor  2 NADH are created by glycolysis; can be used to make ATP  No oxygen needed

43. The Krebs Cycle and Electron Transport  Aerobic part of cellular respiration  The Krebs cycle breaks pyruvic acid into carbon dioxide and water using oxygen

44. The Krebs Cycle a.k.a. Citric Acid Cycle  Pyruvic acid enters mitochondrion from the cytoplasm  1 carbon is broken off as carbon dioxide; 2-carbon compound is left

45.  2-carbon compound binds with coenzyme A to form acetyl- coenzyme A (acetyl-coA)  Acetyl-coA attaches to a 4- carbon compound to form citric acid ( hence the name Citric Acid Cycle )

46.  Through various intermediate stages; 2 more carbons are released as carbon dioxide  A 4-carbon compound is left; this will attach to the next acetyl-coA and the cycle starts over

47. Electron Transport  A series of molecules that uses high-energy electrons to convert ADP into ATP

48. Electron Transport  High energy electrons are passed along the electron transport chain; at the end, there is usually an enzyme that transfers the electrons to oxygen and hydrogen to form water

49.  Every time a pair of electrons travels down the chain, their energy is used to send H + across the membrane.  This creates an area of high H + concentration and an area of low H + concentration

50.  Facilitated diffusion occurs to try to bring H + concentrations to equilibrium  The carrier molecule is ATP synthase which make an ATP for every H + that goes across the membrane  1 pair of high energy electrons = 3 ATP

51. The Totals  Glycolysis = 2 ATP  Krebs/Electron Trans=34ATP  Total36 ATP

52. Fermentation  Anaerobic way to process food to get energy  Everything starts with Glycolysis

53. Alcoholic Fermentation  Pyruvic acid + NADH  alcohol + CO 2 + NAD +  Yeast works on an alcoholic fermentation system

54. Lactic Acid Fermentation  Pyruvic acid + NADH  lactic acid + NAD +  Muscle cells can build up lactic acid when they are forced to work without enough of an oxygen supply

57. Photosynthesis and Cellular Respiration Photosynthesis Cellular Respiration Function Energy storage Energy release LocationChloroplastsMitochondria Reactants CO 2 and H 2 O C 6 H 12 O 6 and O 2 Products CO 2 and H 2 O Equation 6 CO 2 + 6 H 2 O -> C 6 H 12 O 6 + 6O 2 6O 2 + C 6 H 12 O 6 - > 6 CO 2 + 6 H 2 O