Altruism

Altruistic acts serve to benefit the individual’s close relatives, or kin. They enhance the fitness of other individuals—their offspring—at a cost to themselves.

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#Unit 6. System Physiology – Plant

Diurnal phosphorylated PEPCase is active and incorporation of HCO3 – into PEP. Light stimulates PEPCase‐kinase activity

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#Unit 6. System Physiology – Plant

activation of PPDK through the phosphorolytic cleavage (dephosphorylation) of the phosphorylated Thr (Pi‐dependent/PPi‐forming).

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#Unit 6. System Physiology – Plant

Catalytic activity of PPDK is regulated by phosphorylation by the PPDK‐regulatory protein (PPDK‐RP).

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#Unit 6. System Physiology – Plant

In the dark, PEPCase returns to the inactive form because PEPCase‐kinase is inactivated and a phosphatase releases the phosphoryl group from PEPCase.

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#Unit 6. System Physiology – Plant

The biphasic C4 system reduces photorespiration dramatically by increasing levels of CO2 near Rubisco to enable Rubisco carboxylation to outcompete the oxygenation reaction. 

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#Unit 6. System Physiology – Plant

The low photosystem II activity in the bundle sheath also minimizes the Rubisco oxygenation reaction.