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Photosynthesis

Photosynthesis. I. The basics. A. The equation. C 6 H 12 O 6 + 6O 2. 6CO 2 + 6H 2 O . 1. CO 2. a. pulled from the air thru the stomate. b. reduced to -CHO. 2. H 2 O.

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Photosynthesis

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  1. Photosynthesis

  2. I. The basics A. The equation C6H12O6 + 6O2 6CO2 + 6H2O 

  3. 1. CO2 a. pulled from the air thru the stomate b. reduced to -CHO

  4. 2. H2O a. enters the plant thru the roots  xylem  all parts b. oxidized to oxygen c. transpiration -evaporation of water at the leaves….

  5. 3. C6H12O6 a. used in Cellular Respiration to make ATP -C is bond to O2 make CO2

  6. b. excess sugar is stored as STARCH in clusters within the plant: -Cells of fruit -seeds -stems -modified roots -converted to oil & stored in seeds

  7. c. 250,000 known spp. of plants of which ~150 are cultivated -crops: a type of plant that is grown for use by humans -3 Major crops that feed the world:

  8. 4. O2 a. exits thru the stomate b. important byproduct for living org

  9. B. Leaf Structure 1. PS occurs in the __________

  10. 2. Chloroplast has 2 main parts: a. thylakoid… -flattened membrane-bound sacs -sacs are stacked into ______ -chlorophyll is embedded here b. stroma… -fluid matrix of the chloroplast -contains enzymes…

  11. C. How is light Energy used? 1. Light is radiant Energy a. can travel in waves

  12. b. electromagnetic spectrum -complete range of radiant E

  13. c. photons -tiny packets of E d. visible light spectrum - ROY G BIV Longer λ Shorter λ

  14. 2. Light hitting a surface a. the photons are either: (1) reflected (2) absorbed (3) transmitted thru the object b. the color of the plant is the color being reflected….

  15. D. Pigments in plants 1. Pigment a. a molecule containing atoms that enable it to absorb light 2. Chlorophyll a a. primary pigment b. absorbs violet and orange/reds c. reflects green light

  16. 3. accessory pigments a. chlorophyll b b. xanthophyll -reflects yellow c. carotenoids -reflects orange

  17. d. each pigment absorbs diff wavelengths of light…Advantage? e. changing of leaves in the Fall

  18. 4. Pigments are arranged in clusters called photosystem a. embedded in thylakoid membrane b. 2 kinds of photosystems: -Photosystem I: wavelength 700nm -Photosystem II: wavelength 680nm

  19. II. Photosystem II (make ATP) A. How does it work? 1. sunlight is absorbed by pigments in the thylakoid 2. photons boost the e- to a higher E level  EXCITED 3. e- are sent to reaction center..

  20. 4. reaction center donates e- to electron transport chain (ETC) a. ETC is a series of redox rx b. stairs analogy 5. The ETC contains a proton pump a. pumps H+ into the thylakoid … b. [H+] increases and builds up pressure

  21. 6. ETC donates its electrons to Photosystem I a. splitting of 2 H2O molecules: 2 H2O  4 H+ + 4e- + O2 b. H+ are left inside the thylakoid & O2 diffuses out of plant

  22. 7. In the meantime… a. ATP synthase is used for ADP ATP b. chemiosmosis

  23. III. Photosystem I (make NADPH) A. How does it work? 1. sunlight is absorbed by pigments in the thylakoid 2. e- from photosystem II are transferred to reaction center of Photosystem I… 3. e- are sent to reaction center..

  24. 4. reaction center donates e- to electron transport chain (ETC) 5. e- are transferred to a reducing protein a. NADP+ NADPH

  25. IV. Calvin Cycle A. Carbon Fixation 1. CO2 CHO 2. enzymes incorporate carbon atoms from CO2 into organic molecules

  26. 3. Light independent reactions a. does NOT require light directly but does require ATP & NADPH b. requires CO2 that enters thru the stomate 4. There are several ways C is fixed during PS….

  27. B. Melvin Calvin 1. Background a. discovered in 1940-50’s at the Uni of Ca 2. Occurs in all plants and algae… 3. 6 CO2must enter cycle to produce a 6-carbon sugar

  28. C. Steps of the Calvin Cycle 1. Carbon Fixation a. CO2 is attached to RuBP  resulting in a 6-C molecule b. C-C-C-C-C-C  C-C-C + C-C-C PGA

  29. 2. Carbon Reduction a. each molecule of PGA is reduced to PGAL PGA  PGAP  PGAL ATP NADPH

  30. 3. Regeneration of RuBP a. 1 PGAL may combine to make C6H12O6 b. most of the PGAL produced is used to regenerate RuBP -ATP required

  31. 4. The spend ADP & NADP are returned to the light dependent rx to become ATP & NADPH

  32. V. Factors that affect the rate of PS A. Light Intensity 1. PS increases as intensity increases until saturation point is reached

  33. B. CO2 concentration 1. similar to light intensity

  34. C. Temperature 1. PS is a series of enzyme catalyze rxs and they fail outside a particular range

  35. Cellular Respiration

  36. Cellular Respiration Equation C6H12O6 + 6O2 6CO2 + 6H2O + ATP

  37. Electron Transport Chain - 2ATP

  38. I. Cellular Respiration A. Steps 1. Glycolysis a. glucose splits into 2 pyruvate C6H12O6 2 x pyruvate b. occurs in cytoplasm c. +2 ATP…

  39. 2. Acetyl coenzyme-A formation a. pyruvate binds to coenzyme A b. occurs in the mitochondria c. -2 ATP…

  40. 3. Kreb’s Cycle or Citric Acid Cycle a. acetyl co-A molecule enters cycle b. combines with oxaloacetate  citrates CO2 c. occurs in the matrix d. +2 ATP…

  41. 4. ETC a. transfers e- from Kreb’s cycle down a series of protein carriers b. Energy given off is used to make ATP c. terminal e- acceptor is oxygen H2O d. occurs in the inner membrane e. +34 ATP…

  42. B. Exercise Benefits 1. # of mitochondria increase… a. faster rise in O2 uptake at the onset of work less O2 debt 2. Cramps & Charlie Horse..

  43. II. Anaerobic Respiration/Fermentation A. 2 General types of fermentation 1. Alcohol Fermentation 2. Lactic Acid Fermentation

  44. B. Alcohol Fermentation 1. C6H12O6 CO2 + Ethanol + 2 ATP a. performed by microorganisms; bacteria and yeast b. CO2 and bread rising

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