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Unformatted text preview: PHOTOSYNTHESIS (TUNE:“AULD LANG SYNE”) Auld Lang Syne Midi Auld Lang Syne MP3
Object 1 When sunlight bathes the chloroplast, and photons are absorbed The energy’s transduced so fast that food is quickly stored, Photosynthetic greenery traps light the spectrum through Then dark pathway machinery fixes the CO2 Two chlorophylls (a,b to you) are cleverly deployed In photosystems I and II, within the thylakoid System I takes energy, at 700 (red) While system II (with pigment b) takes 680 instead. At manganese on center II, see oxygen displace As water’s split, and protons too, leave membrane inner face Electrons that we thus produce, cross, ‘photo-fortified’ Plastoquinone then to reduce, upon the other side. Meanwhile at I, chlorophyll a is photo-oxidized (At ‘positive holes’, formed that way, electrons are much prized), Electrons that we thus eject reduce NADP With ferredoxin we suspect, as intermediary. The hole in I we now negate, plastoquinol moves in With b and f to mediate, and plastocyanin, That redox loop, potential large, runs exergonically With membrane-separated charge, and thence to ATP That Z track by electron pair, reduced NADP, Plucked oxygen from water’s care, and made some ATP. Now we’ve got power to reduce, and ATP to spare, Food in the dark we can produce, from CO2 in air. Ribulose bisphosphate takes, a mole of CO2 Gives two 3-phosphoglycerates, (if Calvin’s story’s true) NADPH now provides, reducing power to make Two phosphoglyceraldehydes (as ATP we break) There now occurs a jolly jig (the details we’ll ignore) With carbon chains both small and big, to ribulose once more, Each time round, as CO2, is fixed we’ve chains to spare And we can make hexoses new, from triose phosphate pair. Other routes involve C4, or pyruvate to fat, NADPH as before, is vital still for that, ATP still provides the drive, the moral still is this — The one thing that keeps life alive is photosynthesis. ...
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