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