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

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