Cellular Energetics

1. Cellular Energetics

3. Catabolic pathways • Fermentation: Partial degradation (O2) • Cellular respiration: Full degradation (O2) • Organic compounds + O2 CO2 + H2O + energy (gasoline burning) • C6H12O6 + 6O2  6CO2 + 6H2O + energy

4. Redox reactions • Explains how energy is yielded by transfer of electrons • Oxidation: Loss of electrons • Reduction: Gain of electrons (OILRIG) • Na + Cl  Na+ + Cl- (complete transfer) • To pull electrons away from an atom requires input of energy

5. Partial transfer • More electronegative  more energy needed • When electrons shift from less electronegative to more electronegative atom  Electron loses potential energy, which is released as heat

6. C6H12O6 + 6O2  6CO2 + 6H2O + energy • C6H12O6 is oxidized/reduced while O2 is oxidized/reduced C6H12O6 is the _____agent while O2 is the ____ agent. • This reaction is considered exergonic/endergonic, therefore it is spontaneous/not spontaneous and has a +/- change in free energy • Why are many organic molecules great fuels? • When a spark is applied to gasoline and oxygen it burns and releases a LARGE quantity of energy. Why doesn’t glucose do the same thing in the presence of O2 in your body?

7. Enzyme facilitate the break down of organic fuels to CO2 in a SERIES of steps. Why not just one step? • Electrons (along with a proton) are stripped from glucose, but not directly to O2, instead they are transferred to…

8. NAD • Conezyme derived from the vitamin niacin • NADox vs NADre • Very little PE lost • Energy can be tapped into when ATP needs to be made

9. How do electrons finally reach oxygen?

12. Substrate level phosphorylation • Enzymes transfer a phosphate group from the substrate to ADP • In oxidative phosphorylation (discussed tomorrow) inorganic phosphate is added to ADP

13. Glycolysis “splitting of sugar” • Location? • Inputs? • Outputs? • Purpose?

20. Fermentation

22. Lab 5: Cellular Respiration

23. Lab 5: Cellular Respiration • Description • using respirometer to measure rate of O2 production by pea seeds • non-germinating peas • germinating peas • effect of temperature • control for changes in pressure & temperature in room

24. Lab 5: Cellular Respiration • Concepts • respiration • experimental design • control vs. experimental • function of KOH • function of vial with only glass beads

25. Lab 5: Cellular Respiration • Conclusions • temp = respiration • germination = respiration calculate rate?

26. Sources of energy Photosynthesis (photoautotroph) Autotrophs (self-feed from CO2 and inorganic materials): plants, some algae, some bacteria Synonym: Producers Chemosynthesis (chemoautotroph)

27. Chloroplast structure Read through :birth of complex cells to get further detail about other plastids and organelles such as peroxisomes Water: rootsveinsmesophyll cells Sugar: mesophyll cellsveinsrest of plant CO2, O2  stomata

28. Absorbing/reflecting light • Problem: How do plants utilize energy from light to produce carbohydrates? • Properties of light • While traveling, acts as a wave (properties depend on this wavelength) • When interacting with matter (like your clothes) acts as a particle • Photon: Discrete packet of light

29. Pigment structure/function

30. Pigment structure/function • When chlorophyll absorbs light, energy is transferred to electrons. Plant pigments Chlorophyll a: primary pigment Chlorophyll b: broadens range of wavelengths that can be used Carotenoids: Also broadens range, absorbs, dissipates excessive energy, prevents interaction w/ O2 EAT YOUR CARROTS, why?

31. Light dependent reactions • Role of chlorophyll: Capture energy from light • Role of an electron carrier: transport electrons which carry the energy initially from light (NADP+ + 2e- + H+  NADPH)

32. 6CO2 + 6H2O light> C6H12O6 + 6O2 • Where does the O2 come from? • Hypothesis 1: CO2 + C  C + O2 C + H2O  CH2O • Hypothesis 2 (van Niels) • Studies bacteria that DIDN’t produce O2 • CO2 + 2H2S  CH2O + H2O + 2S • CO2 + 2H2O CH2O + H2O + O2 • Confirmed with radioactive tracers to track its fate Visible globules

33. REDOX chemistry • REDOX! Water is split  electrons and Hydrogen ions to CO2. Electrons increase in potential energy, so energy is NEEDED! (endergonic, +ΔG) • CO2 is reduced to sugar • H2O is oxidized

34. Photosynthesis overview • NADP+ : Same function as NAD+ • Photophosphorylation

35. How do photosystems work? • Only photons with energy equal to the atoms ground state excited stated is absorbed Why does isolated chlorophyll fluoresce? Redox

36. Noncylic electron flow

37. Noncylic electron flow

38. Noncylic electron flow

39. Noncylic electron flow

40. Noncylic electron flow

41. Noncylic electron flow

42. Cyclin electron flow Function: Regenerate ATP lost through Calvin Cycle (more ATP consumed than NADPH)

43. Electron transport chain Location: _____ Input: ______ Output: ___ Purpose: _____

44. Chemiosmosis comparison

45. Calvin Cycle • Purpose: _____ • Location: ____ • Input : ____ • Output : ____

47. Lab 4: Photosynthesis

48. Lab 4: Photosynthesis • Description • determine rate of photosynthesis under different conditions • light vs. dark • boiled vs. unboiled chloroplasts • chloroplasts vs. no chloroplasts • use DPIP in place of NADP+ • DPIPox = blue • DPIPred = clear • measure light transmittance • paper chromatography to separate plant pigments

49. Lab 4: Photosynthesis • Concepts • photosynthesis • Photosystem 1 • NADPH • chlorophylls & other plant pigments • chlorophyll a • chlorophyll b • xanthophylls • carotenoids • experimental design • control vs. experimental

50. Lab 4: Photosynthesis • Conclusions • Pigments • pigments move at different rates based on solubility in solvent • Photosynthesis • light & unboiled chloroplasts produced highest rate of photosynthesis Which is the control? #2 (DPIP + chloroplasts + light)