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

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