Enzymes responsible for PTJ Helicase is hexameric and motor that melts the duplex and requires ATP hydrolysis—typically 1 ATP is hydrolyzed for each base pair that is unwound.

TLS Online TPP Program

#Id: 8836

#Unit 6. System Physiology – Plant

TLS Online TPP Program

#Id: 8837

#Unit 6. System Physiology – Plant

The ascorbate-glutathione pathway (Halliwell-Asada cycle) is an indispensible component of the ROS homeostasis mechanism of plants.

TLS Online TPP Program

#Id: 8838

#Unit 6. System Physiology – Plant

The biosynthesis of chlorophylls and heme begins with the synthesis of δ‐aminolevulinic acid (ALA) from glutamic acid. 

Two molecules of ALA react to yield porphobilinogen (PBG). 

Four molecules of PBG form the ring structure of protoporphyrin IX, the common branch point for the synthesis of heme and chlorophyll. 

To make chlorophyll, a magnesium chelatase inserts Mg into the protoporphyrin IX ring

TLS Online TPP Program

#Id: 8994

#Unit 6. System Physiology – Plant

Carboxylation of the CO2 acceptor molecule. 

The first committed enzymatic step in the cycle is the reaction of CO2 and water with a five-carbon acceptor molecule (ribulose 1,5-bisphosphate) to generate two molecules of a three-carbon intermediate (3-phosphoglycerate).

TLS Online TPP Program

#Id: 8995

#Unit 6. System Physiology – Plant

Reduction of 3-phosphoglycerate. The 3-phosphoglycerate is converted to three-carbon carbohydrates (triose phosphates) by enzymatic reactions driven by photochemically generated ATP and NADPH.

TLS Online TPP Program

#Id: 8996

#Unit 6. System Physiology – Plant

Regeneration of the CO2 acceptor ribulose 1,5-bisphosphate. 

The cycle is completed by regeneration of ribulose 1,5-bisphosphate through a series of ten enzyme-catalyzed reactions, one requiring ATP.