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C4 Photosynthesis. Alternate pathway to C3 “dark reactions”. How it differs from C3 photosynthesis. Carbon dioxide is “fixed” by PEP to form OAA instead of carbon dioxide being “fixed by rubisco to form PGA OAA (the first product made) has 4 carbons Less oxygen to compete with
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C4 Photosynthesis Alternate pathway to C3 “dark reactions”
How it differs from C3 photosynthesis • Carbon dioxide is “fixed” by PEP to form OAA instead of carbon dioxide being “fixed by rubisco to form PGA • OAA (the first product made) has 4 carbons • Less oxygen to compete with • Water loss is reduced • Overall, more efficient than C3
C4 Reaction Summary • Carbon dioxide enters leaf • Combines with PEP & “fixed” by PEP carboxylase to form OAA • OAA converted to malate • Malate sent to bundle sheath cells • Very little oxygen ever comes in contact with bundle sheath cells, making this cycle more efficient
Other things about C4 • Stomata doesn’t have to stay open as much • These plants found in dry, hot areas • Sugarcane and crabgrass are examples