🎵 Luyện Nghe Bài Hát: Photosynthesis - The Light Reactions - Glenn Wolkenfeld

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