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 Photosynthesis : part A -  Light Reactions
 Amusical Lecture  Glenn Wolkenfeld
 
 A music  by Glenn Wolkenfeld
 Boys and girls tell me what you think  this,
 Time for a lesson ‘bout 
 Cells use light to combine water  dioxide.
 Gonna see electrons going for a  ride.
 Making  making sweet O¬2.
 But  should photosynthesis matter to you?
 Food on your 
 O2 rich atmosphere.
 Without photosynthesis you simple wouldn’d  here.
 
  Part I, The Big Picture)
 Photosynthesis is a  reaction.
 Powered by light  enzymatic action.
 Water’s  CO2’s re duced
 The sugar that results you drink in orange 
 The overall reaction has  phases.
 First is the light  which has as its basis.
  powered production of ATP.
 O2 is the by  product and you will see.
 Production  electron carrier NADPH
 Which provides reducing power  in the second phase
  NADPH, during phase 2
 Provides what’s  for reducing CO2
 NADPH ia made by a  of NADP+, whose function
 Is to absorb electrons and  up H,
 Gaining  and making NADPH.
 Phase  is the Calvin Cycle makes carbohydrate,
 Like sugar and starches and fibers on your lunch 
 It’s how plants  food animals eat.
 Photosynthesis,  so sweet!
 
 (Part II: Chloroplasts, Thylakoids, Light, and 
 In a lesf  mesophyllic tissue
 And  with chloroplasts key to the issue.
 Chloroplasts are  like cells in every way,
  their own ribosomes and their own DNA.
 They even reproduce themselves, splitting  half.
  clue for this organelle’s independent past.
 This theory  a name endosymbiosis,
 Developed in  60s by Lynn Margulis.
 Inside the chloroplast  the fluid stroma.
 It’s  in Tokyo.
 It’s true in 
  syrrounds little thylakoids.
 Each one has  hollow space inside.
 The thylakoid’s membrane  loaded with protein.
 ‘Cause it’s  light reactions’ scene.
 It’s all about using  for powering electrons,
 All about grabbing  power in photons.
 The  needed are are those from light,
 Which has the energy  make the world bright.
 The  frequency that we can see,
  violet light with wavelength 380.
 380 nanometers,  small,
 But next to gamma rays it’s  tall.
  light shines at 750.
 Isn’t the visible spectrum 
  are packets of light energy,
 Both a  and a particle, you see.
 Phootins get adsorbed  pigments.
 It’s real, it’s true,  ain’t no figment!
 Most important  green chlorophylls.
 Orange carotenoids, and  xanthophylls.
 Together they absorb  mostly red and blue.
 The green  not absorbed it reflects back to you.
 In chlorophyll see  porphyrin ring.
 See the magnesium, which makes you want  sing,
 Magnesium,  with valence two.
  see those electrons rocketing through.
 Notice the tail, a  chain.
 Which anchors chlorophyll into  thylakoid membrane.
 A  with style, so pretty,
 In the thylakoid it makes 
 
 ( Part III)
 Englemann showed us  action spectrum.
 Used a prism  break the sun’s
 Light into  frequencies.
 Shone it on  filamentous algae.
 The O2 algae make will stimulate 
 Which will grow in any oxygen  rich area.
  loved it over blue and red,
 But hardly grew over green, they might as well  dead!
 The line of growth is a refection, of photosynthesis’ action 
 Note  won’t match, exactly,
  absorption spectra of chlorophyll a or b.
 ‘Cause the cartenoids and xanthophylls we’ve 
 Absorb light frequencies  chlorophylls can’t get.
 And in the thylakoid they  cooperate,
 In  light to synthesize carbohydrate.
 Consider chlorophyll  isolation,
  some light upon it (call it photoexcitation)
  valence electrons in magnessium
  to an excited state, it’s so fun!
 But once  at that level, they can only fall.
 Back to  they started, like a bouncing ball.
  falling alectrons, release energy,
 Fluorescing as red light,  you can see.
  in thylakoids, chlorophyll’s not alone,
 Instesd a photosystem is  home.
 The photosystem’s  can take photons,
 And use their energy  move electrons.
 The system’s antenna complex does the first 
 Changing photon anergy into  rapture.
 The energized electrons  like a ball,
 At  reaction center, they jump but do not fall.
 A primary electron  grabs them from on top,
 And yanks them  a force reaction center cannot stop.
 To this oxidized  center we’ll return,
 But the details of electron flow it now is time to 
 
 ( Part IV) ATP Synthesis in Non –  Electron Flow.
 Non -  cycle flow is the main 
 Much confustion  to the way
 Hootoystm  precedes photosystem I.
 It’s a fct to memorize, just get it 
  II’s antenna captures a photon,
 Generates  flow of electrons.
  around the world, even n Haiti,
  flow to reaction center P680.
 There electrons  not hover,
 Electron  passes them over.
 To the electron transport 
  the thylakoid membrane.
  chain’s like a bucket brigade.
 Each molecule has a similar 
  take energized electrons,
 And use their energy for pumping 
 From stroma  the thylakoid space.
 Packing protons into that 
 This makes a gradient across the thylkoid 
 The protons want “out” or they’ll go 
 But the protons can’t 
 The membrane won’t allow 
 There’s only one port  which they travel.
 It’s  ATP Synthase channel.
 The “-ase” tells you this  an enzyme.
 Which makes ATP all the 
 It has binding sites for  and Pi,
 And  for diffusing protons whose knetic energy.
  the binding sites’ conformation.
 Fusing ADP with  which for your information.
  how thylakoids make ATP.
 Life’s key form of 
 From respiration this might  familiar.
 ATP is  this way in mitochondria.
 Chemiosomosis  the name
 ATP production  the game.
 
 ( Part  NADPH Synthesis in Non – Cyclic Elecron Flow)
 Back to our electons moved  the sun.
 Flowing from Photosystem II  System I.
 They get to PS I  a used up battery.
 The transport  used up their energy.
 But when light hits  I’s antenna
  boune to reaction center.
 This one’s P700,
 That  makes electrons go!
 PS T’s electron acceptor  them away,
 Leaving P700 in an oxidized 
 And P700 with its  blues accepts the alectrons from PS II.
 Bak to  from PS I.
 It now gose for a ride, having  own fun.
 But powering proton pumps  its fate.
 It travels to  reductase.
 An enzyme  cells count upon.
  pass some H and electrons.
  NADP+ which gets reduced.
 It’s how  get produced.
 
 (Part VI: Oxygen Production in  – Cycli Electron Flow)
  by – product of these light reactions
 Is oxygen  how it happens.
 Back  II, it came to arise,
 That P680 got 
 To replace lost  P680 liberates.
 Electrons  water which dissociates.
 Into one oxygen and protons 
  single O will meet anoher forming O2.
 These protons are  in the thylakoid space.
 Increasing proton concentration in that 
 So we  a side effect of water’s oxidation.
 Is enhancement  ATP creation.