C4, PUMP IT UP!

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C4, PUMP IT UP!

• Dr. Weise

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C3, History of Discovery

• Andrew Benson
• James Bassham
• Melvin Calvin UC Berkley
• 1949 Discovered radioactive CO2 fed to algae
  first goes into PGA a 3 Carbon Compound

• Calvin solely won the Nobel Prize in Chemistry
  1961

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C4, History of Discovery

• Hugo Kortschak Hawaiian Sugar Planters Research
  Lab
• 1965 Radioactive CO2
• fed to sugar cane first goes
• into malate a 4 carbon compound

• Got scooped by Hal Hatch and Rodger Slack

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C4, History of Discovery

• Hal Hatch and Rodger Slack - Colonial Sugar
  Refining Co, Brisbane
• By 1969 had elucidated complete pathway we know
  today
• Was initially called the Hatch Slack Pathway

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C4, Only an Addition to the Calvin Cycle
C4 Front End
Pyruvate
PEP (3C)
Pyruvate (3C)
CO2
PEP carboxylase
OAA (4C)
Malate (4C)
Malate(4C)
Mesophyll Cell
Bundle Sheath Cell
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Kranz Anatomy
Definitely Not This!!
Not Greys Anatomy
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C4 Isnt about CO2 (sorta)

• Its all about water and temperature

• At high temperatures rubsico gets sloppy
• Catalyzes more oxygenations
• Plant looses carbon and energy

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What About the Water?

• Plants have pores too, we call them stomata

• To let in CO2 plant must let out Water

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C4

• C4 acts as a CO2 pump for the Calvin cycle
• C4 can be twice as efficient at conserving water
  at higher temperatures
• PEP Carboxylase has a much higher affinity for
  CO2 than rubisco allowing those stomates to stay
  closed conserving water
• But there is a price..High ATP usage