The thin segment of the ascending limb has a much lower reabsorptive capacity than does the thick segment.

TLS Online TPP Program

#Id: 9013

#Unit 6. System Physiology – Plant

Rubisco is inhibited by the natural inhibitor 2‐carboxyarabinitol 1‐phosphate (CA1P), that is a structural analog of the six-carbon intermediate of the carboxylation reaction. 

TLS Online TPP Program

#Id: 9014

#Unit 6. System Physiology – Plant

TLS Online TPP Program

#Id: 9015

#Unit 6. System Physiology – Plant

CA1P and the other bound sugar phosphates are specifically removed by the ATP‐dependent enzyme, Rubisco activase, which prepares Rubisco for the catalytic cycle.

TLS Online TPP Program

#Id: 9016

#Unit 6. System Physiology – Plant

When dark‐treated chloroplasts are exposed to light;

The flow of protons from the stroma into the thylakoid lumen is coupled to the release of Mg2+ from the intrathylakoid space to the stroma.

TLS Online TPP Program

#Id: 9017

#Unit 6. System Physiology – Plant

When dark‐treated chloroplasts are exposed to light

These light actuated ion fluxes decrease the stromal concentration of protons (the pH increases from 7 to 8) and increase that of Mg2+ by 2 to 5 mM. 

TLS Online TPP Program

#Id: 9018

#Unit 6. System Physiology – Plant

When dark‐treated chloroplasts are exposed to light

activate enzymes of the Calvin–Benson cycle that require Mg2+ for catalysis and are more active at pH 8 than at pH 7 for STROMA