Photosynthesis

  1. Photosynthesis
    process in plants of breaking down carbon dioxide and oxygen into glucose with he assistance of sunlight
  2. Chlorophyll "a"
    main type of chlorophyll that all plants have
  3. Accessory pigments
    • absorb energy that chlorophyll "a" does not absorb
    • such as chlorophyll b, c, d, e 
    • carotenoids (blood orange)
  4. Different pigments' purpose
    • to absorb different waves of energy
    • different pigments absorb different, specific kinds of energy
  5. Leaves in autumn
    change colour because the light is received by the leaf at a different angle, therefore different wavelengths/colours are absorbed by the leaf
  6. Senescence
    • trees talking using hormones
    • why all trees' leaves change colour at same time
  7. Chloroplast
    organelle
  8. Chlorophyll
    pigment/colour
  9. Xylem
    • dead cells/tissue
    • transports water
  10. Phloem
    • living cells
    • transports sugars
  11. Stomata
    exchange gases
  12. Cuticle, epidermis
    • prevent water loss
    • Cuticle is waxy, wax is an oil, water cannot escape past this oily waxy layer of the leaf
  13. Palisade mesophyll cells
    contain chloroplasts
  14. Thylakoid
    • system of interconnected flattened membrane sacs
    • stack on top of each other, forming grana (multiple thylakoids stacked)
  15. Lamellae
    structural support
  16. Photosynthesis
    • occurs in thylakoid, stroma
    • thylakoid: light dependent reactions, has pigment, traps light, so light is used
    • stroma: light independent reactions, does not need any light
  17. ATP role
    splits H2O, CO2, to make glucose (energy)
  18. NADPH
    • holds electrons, gives electrons to something else
    • made of an NADP, and an H
    • NADP is positively charged, therefore bonds with two e- to balance out
  19. Photosynthesis stages
    • 1. capture solar energy and transfer it to e-
    • 2. use captured solar energy to make ATP; transfer high energy e- to NADP+: NADPH is then used as a high energy e- carrier
    • 3.
  20. Reactants of photosynthesis are the products of
    cellular respiration
  21. Light independent stage (stage 3 of photosynthesis)
    • occurs during either day or night
    • a.k.a. Calvin cycle
    • carbon fixation occurs: incorporation of CO2 into organic compounds such as glucose
    • occurs in stroma or chloroplast
    • uses ATP and NADPH from light dependent reactions
  22. Stroma
    gel-like fluid inside of chloroplast
  23. Capturing solar energy (stage 1 of photosynthesis)
    • occurs in thylakoid membranes
    • cluster of chlorophyll and other pigments 
    • photosystem 1 uses chlorophyll "a"
    • photosystem 2 uses a slightly different form of chlorophyll "a"
    • photosystems operate so that a wide range of wavelengths can be used for photosynthesis
    • photosystem 2 occurs first, then photosystem 1 occurs second
    • 2 energized e- are removed from photosystem 2 from chlorophyll
    • e- enters an electron transfer chain
  24. Photosystem
    • areas where light is being captured
    • photosystem 2 makes NADPH
    • photosystem 1 makes ATP
  25. Redox
    • any time when an electron is moved
    • ANY
    • A N Y
    • literally any time
  26. Electron transfer chain
    • hot potato, basically of electrons
    • ATP is made because of the energy release through the chain
  27. Photolysis
    • occurs in thylakoid lumen
    • literally "light cut"
    • solar energy absorbed by chlorophyll is used to split water into H, e-, O2
    • e- travels to photosystem 2
    • O exits thru stomata or is used to make H2O
    • H will be used later to reduce ADP
  28. Electron transfer and ATP synthesis events
    • a) e-, excited by light at photosystem 2, are passed along an ETC
    • e- releases energy at every step
    • b) energy from e- is used to pull H+ ions across membrane into lumen
    • e- have lost most of their energy
    • H+ ion concentration builds up and so does a positive charge 
    • c) e- are transferred from ETC to photosystem 1
    • d) e- are transferred to NADPH
  29. Chemiosmosis
    • diffusion based on concentration of positive Hydrogen ions (high to low)
    • electrical gradient results
    • H+ ions rush through ATP synthase complex
    • in doing so, H+ ions generate energy
    • this energy is used to create ATP
    • this energy in H+ ions comes from the sun originally
    • ATP synthase complex is in the thylakoid membrane
  30. Light independent reactions
    • happens in stroma
    • Calvin-Benson cycle and carbon fixation
    • carbon fixation = turning CO2 into glucose
    • upon entering Calvin cycle, carbon is reduced
    • direct product of Calvin cycle is G3P/PGAL, precursor to glucose
  31. Stage 3: Light independent reactions continued
    • C, O atoms provided by CO2
    • H atoms provided by photolysis of H2O
    • 3 ATP, 2 NADPH are used per each CO2 that enters the Calvin cycle
    • the building of one glucose molecule requires 18 ATPs, 12 NADPHs
  32. Stages of Calvin cycle/carbon fixation
    • 1. CO2 fixation, reduction
    • 2. PGAL/G3P molecules produced
    • 3. regeneration of RUBP
    • each stage requires enzymes to occur
    • RUBP + CO2 -> unstable 6 - C molecule
    • 6 - C molecule breaks down into two 3 - C molecules (PGA)
  33. Calvin cycle step 1
    • RUBP (ribulose biphosphate) 5 carbon molecules long, attaches to CO2
    • enzyme for this reaction is RUBP carboxylase
  34. Calvin cycle step 2
    • each 3 PGA molecule gets reduced; ATP and NADPH provide this step
    • 3 C PGA is reduced to form PGAL and water
  35. Calvin cycle step 3
    • direct product - PGAL
    • glucose: six revolutions of Calvin cycle required for one molecule of glucose
    • 6 H2O
    • (ADP, P, NADP+, H+) - products of photosynthesis
  36. Lumen
    space inside of thylakoid itself
  37. Final electron acceptor in ETC
    O2
Author
Alex16
ID
355428
Card Set
Photosynthesis
Description
Updated