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

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