photosysthesis presentation

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Photosynthesislifes basic Rx!

• Basic questions
• Some history
• Some plant anatomy
• Some biochemistry light reactions dark
  reactions photolysis

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Basic questions??

• What do plants eat?
• Why do plants need light?
• Why do plants need water?
• Why are plants green?

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Some HistoryGreeks to ?

• what do plants eat?
• VanHelmonts tree
• Priestly phlogiston
• Lavoisier lost his head over some O2well?
• Englemann bacteria?
• Melvin Calvin 1948!

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Summary of photosynthesis ???

• CO2, H2O and light go in
• Carbohydrate and O2 come out
• 6CO26H2O
• C6H12O6O2

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Anatomy of a leaf

• Function(s)??
• Collect sunlight
• Make food
• Move food to storage
• Thus
• Structure related to function

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WHY ARE LEAVES GREEN???
ENLARGE
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Summary of the chloroplast

• Double membranes
• Thylakoid disks called grana (chlorophyll)
• Stroma
• ETS
• loose enzymes

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2 sets of photosynthetic reactions

• Light dependent
• Light energy captured
• 3 reactions
• Light independent
• Calvin cycle
• Makes pyruvate (C3)

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• What is light?
• What are photons?
• Energy photons

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What is chlorophyll?

• Plant pigment
• Imbedded in membrane of thylakoid disks
• Why green?

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• What colors are absorbed?
• What colors reflected?

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QUIZ

• Why are leaves green?
• Relate chloroplast to mitochondria
• What is chlorophyll?
• What cell organelle contains chlorophyll?

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How is light captured?

• How to grab a photon?
• How to hold onto the hot potato (energy of
  photon)

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Quiz

• What are the units of light?
• What colors are captured?
• How are photons captured?

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3 light dependent reactions

• Photosystem Icyclic photophosphorylation
• Photosystem IInoncyclic photophosphorylation
• photolysis

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The Light Reactions
(light dependent)

• Cyclic Photo-phosphorylation (photosystem I)
• Noncyclic Photo-phosphorylation (photosystem II)
• Photolysis

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Cyclic photophosphorylation
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Cyclic photophosphorylation

• Photon excites e-
• e- absorbed
• e- passed thru ETS
• ATP generated via chemiosmosis
• e- recycled

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photosystem I
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Quiz

• Whats produced in photo I?
• How is ATP made?
• What happens to the electron?

• ATP
• Chemiosmosis
• recycled

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Noncyclic photophosporylation

• NADH
• Oxygen
• ATP (chemiosmosis)
• Electron IS NOT recycled

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photolysis
photosystem II
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Quiz photosystem II photolysis

• What is made?
• How is ATP made?
• What is the importance of O2?

• ATP, NADPH, O2
• Chemisosmosis
• Free oxygen released thus changing the worldwhy??

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Products of light reactions

• ATP (via chemiosmosis)
• NADPH
• Oxygen
• What happens to these? And
• What about night?

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What happens during dark Rx (light
independent reactions)

• CO2 from air is fixed
• ATP NADPH carry energy from light Rx
• C3pyruvate (PGA) is formed
• 2X turnsC6?
• C6gtorganic stuff

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The Calvin-Benson Cycle

• How to store ATP?
• Why reinvent the wheel?
• Long-term storage?

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ribulose bisphosphate carboyxlase
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Calvin cycle
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Quiz-Dark reactions (Calvin cycle)

• Why are these reactions called dark
• What are the products of the Calvin cycle?
• Where in the chloroplast do these Rx occur?
• What kinds of molecules can be made from PGAL
  (pyruvate)?
• What is the most prevalent protein on the planet?
  Why is it so important?

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Alternative pathways??

• Why is the former called C3pathway?
• photorespiration?
• C4
• CAM
• Not as efficient as C3 but, hey.beats nothing?

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Photosynthesis summary
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Energy flow in nature
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Energy pathways in photosynthesis