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

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