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 Photosynthesis
  Cyclic Electron Flow and The Calvin Cycle
 Amusical Lecture by  Wolkenfeld
 
 Thanks for joining us  Episode Two,
  more ‘bout photosynthesic waits for you.
 We last saw how plant cells create, O¬¬2,  and NADPH.
 Now we’ll start with a twist on the  reactions,
 Called cyclic flow, we’ll see how it 
 Then we will investigate how  Calvin Cycle makes carbohydrate.
 
 (Part  Cyclic Electron Flow)
 Non – cyclic flow is also called the “Z – scheme” Put Z  its site and see what I mean.
 Electrons rise in energy  fall and rise again.
 Making ATP  NADPH my friends.
 A variation  this is cyclic flow.
 Which makes  no NADPH or O.
  flow results from the Calvin Cycle’s needs.
 It uses less  than ATP.
 NADPH buildup has the repercussion,  inhibiting NADP+ reduction.
 ‘cause  clogs up reductase.
 Keepping NADP+  moving into place.
 So electrons  go to NADP+.
 They’re clogged, stuck like a  pus.
 Where can they go  P700?
 Nature evolved them  place to flow.
 A shunt pathway moves them  the ETC.
 I’m talking ‘bout the one in PS II  see.
 These energized  flow and release energy.
 Which as you  is used to synthesize ATP.
 
 (  II: Calvin Cycle)
 Now it’s time to learn the cycle named  Calvin.
 Which results in  fixation of carbon.
 Consider that each carbon in your  blood and hair,
 Was once  a CO2 in the air.
  Calvin Cycle has three parts.
 Fixation of  is how it starts.
  molecules produced rae then reduced.
 ‘cause reduction  the key thing that happens in part 2.
 Part 2 is the  as you will see.
 It  molecule G3P
 A reduced molecule with lots of 
 And a starting point for all the  that cells need.
 Part 3 sets up conditions for the cycle’s 
 By recreating what’s  the cycle’s heart.
 RuBP (Ribulose Bisphosphate), a five  molecule that seems to apparate.
  RuBP’s at the cycle’s start.
 Then reappears  the very last part.
 The role  RuBP at the start and end.
 Is  this is a cycle like the one named Krebs.
 The cycle’s inputs are know to  NADPH and ATP and CO2
 Fixation of carbon is catalyzed  RuBP Carboxylase Enzyme
 This enzyme’s  you should know.
 Sounds like a cookie maker:  RUBISCO.
 An  so old it was already here,
 Before O2  in the air.
  CO2 enters through leaf stoma, diffusing through the leaf and arriving at the stroma.
 There RuBisCO grabs it in its active site, and squeezes  with RuBP tight.
 RuBP  carbons five, it has two phosphates, one on each side.
  CO2 combines with RuBP it makes a six carbon compound you won’t see.
 It instantly  into two 3 – phosphoglycerates,
 Each with three carbons and  phosphate.
 Each  phosphorylated to bisphosohoglycerate.
 Phosohorylated means that each receives aphosphate  from ATP.
 This phospharylation,  followed by reduction.
 And you know there’s  enzyme with the function.
 Of taking electrons and H from NADPH and adding them to to 
 Take off a  for Glycealdehyde – Phosphate.
 A starting point for compounds  carbohydrates.
 
 (Part III: Calvin Cycle, 
 Glyceraldehyde-  – phosphat, known as G3P,
 as a product  harvest, and I hope you see,
 how  reactions NADPH and ATP,
 are needed to fix CO2  make organic energy.
 And to complete the cycle  must now regenerate.
  starting point of Calvin Cycle ribulose bisphosphate.
 The intermediates involved in taking 
 And recombining  into RuBPs.
 Are too much  freshman biology.
 You  get the details when you get yors Ph. D.
  know for now that to get 3 RuBPs from 5 G3Ps cost 3 ATPs!
 
 (Part IV: Conclusion)
 Now this journey ends  its emphasis,
  the reaction of photosynthesis.
 For over  billion years it’s been the food chains basis.
 In fossils from that era you can  the traces,
 Of tiny cells  prokaryotic form.
 Stromatolites that lived  waters warm.
 Through photosynthesis they  our planet,
 So aerobic life  live upon it.
 And so  sentient beings who can analyze,
 How  can photosynthesize.
 You could say that photosynthesis gave birth to codiyions for  ciousness on Planet Earth!