In heart muscle, activation series of the muscarinic acetylcholine receptor its effector K+ channel via the Gβγ subunit of a Gi protein.

a. Binding of acetylcholine triggers activation of the Gαi subunit and its dissociation from the Gβγ subunit in the usual way. 

b. The released Gβγ subunit (rather than Gαi∙GTP) binds to and opens the associated effector protein, a K+ channel. 

b. The increase in K+ permeability hyperpolarizes the membrane, which reduces the frequency of heart muscle contraction. 

d. Activation is terminated when the GTP bound to Gαi is hydrolyzed (by a GAP enzyme that is an intrinsic part of the Gαi subunit) to GDP and Gαi∙GDP recombines with Gβγ.

#Question id: 10145

#Unit 6. System Physiology – Plant

The transfer of a phosphoryl group to 3-phosphoglycerate, yielding formation of 1,3-bisphosphoglycerate is catalyze by

#Question id: 10146

#Unit 6. System Physiology – Plant

Light-dependent ion movements modulate enzymes of the Calvin–Benson cycle such as : rubisco, fructose 1,6-bisphosphatase, sedoheptulose 1,7-bisphosphatase, and phosphoribulokinase what will happen Upon illumination;

#Question id: 10147

#Unit 6. System Physiology – Plant

Which of the following enzymes is regulated by supramolecular assembly ?

#Question id: 10148

#Unit 6. System Physiology – Plant

How light controls the assembly of chloroplast enzymes into supramolecular complexes?

a.) Light regulates the stability of the ternary complex through the ferredoxin–thioredoxin system

b.) Reduced thioredoxin cleaves the disulfide bonds of both phosphoribulokinase and CP12, releasing glyceraldehyde-3-phosphate dehydrogenase and phosphoribulokinase in the catalytically active conformations

c.) Oxidised thioredoxin cleaves the disulfide bonds of both phosphoglyceratekinase and CP12, releasing glyceraldehyde-3-phosphate dehydrogenase and phosphoglyceratekinase in the catalytically active conformations

d.) thioredoxin system oxidised the disulfide bonds and reduces the assembly of between chloroplast enzymes and CP12 and converted into the catalytically active conformations

Which of the following statement is correct?

#Question id: 10149

#Unit 6. System Physiology – Plant

Formation of supramolecular complexes with regulatory proteins how effects on the catalytic activity of chloroplast enzymes in the dark as well as in the light?

a.) glyceraldehyde-3-phosphate dehydrogenase binds noncovalently with phosphoribulokinase and CP12 form a ternary complex, wherein glyceraldehyde-3-phosphate dehydrogenase and phosphoribulokinase are catalytically inactive in the dark condition

b.) The A2B2 glyceraldehyde-3-phosphate dehydrogenase can form the A8B8 oligomer, Under dark conditions

c.) Reduced thioredoxin cleaves the disulfide bonds of CP12 and phosphoribulokinase, due to the reduction separates the components of the ternary complex releasing the active phosphoribulokinase and the active A4B4-glyceraldehyde 3-phosphate dehydrogenase under the light condition

d.) Reduced thioredoxin (Trx) cleaves the disulfide bond in subunit B of A8B8-glyceraldehyde-3-phosphate dehydrogenase, the reduction converts the active oligomer into the inactive A2B2-glyceraldehyde3-phosphate dehydrogenase under the light condition

Which of the following combination about catalytic activity in dark and the light is true?

#Question id: 10150

#Unit 6. System Physiology – Plant

Light controls the assembly of chloroplast enzymes into supramolecular complexes one of the enzyme such as Glyceraldehyde-3-P dehydrogenase, this enzyme acivity is dependent on