Which of the following statements about the pentose phosphate pathway is correct?

#Question id: 10279

#Unit 6. System Physiology – Plant

Phosphohexose isomerase is one of the enzyme of glycolysis which catalyzes Glucose 6-phosphate to Fructose 6-phosphate, enzyme bind with the hexose in their active site by opening the structure. The ring opening and closing reactions are catalyzed by an active-site present amino acid such as

#Question id: 10280

#Unit 6. System Physiology – Plant

The enzyme of glycolytic pathway that forms fructose 1,6-bisphosphate is called phosphofructokinase-1 (PFK-1), which statements can’t distinguish it from a second enzyme (PFK-2) Phosphofructokinase-2.

#Question id: 10281

#Unit 6. System Physiology – Plant

Gluconeogenesis is particularly important in plants such as the castor oil plant Ricinus communis and sunflower that store carbon in which form .

#Question id: 10282

#Unit 6. System Physiology – Plant

In the glycolytic reaction one of the step is catalyzed by ATP-dependent phosphofructokinase is essentially irreversible, at the same step which one of the following enzyme used in gluconeogenesis, both of the enzymes are ATP dependent.

#Question id: 10283

#Unit 6. System Physiology – Plant

How to Phosphofructokinase-1 (PFK-1) and Fructose 1,6-Bisphosphatase are reciprocally regulated ?

a) ATP inhibits PFK-1 by binding to an allosteric site and lowering the affinity of the enzyme for its substrate fructose 6-phosphate

b) citrate is also an allosteric regulator of PFK-1, high citrate concentration increases the inhibitory effect of ATP

c) FBPase-1, is strongly inhibited (allosterically) by AMP; when the cell’s supply of ATP is low (corresponding to high AMP), the ATP-requiring synthesis of glucose slows

d) AMP inhibits PFK-1 by binding to an allosteric site and lowering the affinity of the enzyme for its substrate fructose 6-phosphate

Which of the following statements of regulation of enzyme is correct?

#Question id: 10284

#Unit 6. System Physiology – Plant

Allosteric regulation of enzyme multisubunit or multiactive site shows cooperativity with the sigmoidal graph between substerate conc. v/s Activity,

a) Cell contain NADH, FADH2 and ATP, that inhibits the allosteric enzyme activity by lowering the affinity with its substate, graph shifts towards B from control

 b) A- shows low ATP, the Km for fructose 6-phosphate is relatively low, the affinity of the enzyme with its substate is relatively high

 c) Haemoglobin, Phosphofructokinase, Phosphate dehydrogenase complex, α-ketoglutarate dehydrogenase complex, these all enzymes shows characteristics of sigmoidal graph

 d) When ATP is high, Km for fructose 6-phosphate is greatly increased- this activity shown by B in the graph

 e) fructose 2,6-bisphosphate binds to its allosteric site on PFK-1, it increases the enzyme’s affinity for its substrate fructose 6-phosphate and reduces its affinity for the allosteric inhibitors ATP and citrate- shown in graph by A

 Which of the following  combination of the enzyme activity with its substate correctly shown;