The nitrogenase enzyme complex fixes N2 produces ammonia, The nitrogenase enzyme complex catalyzes this reaction by following characteristics given below;

a) It can be separated into two components—the Fe protein and the MoFe protein— neither of which has catalytic activity by itself

b) Fe protein is the smaller of the two components and has two identical subunits, each contains an iron–sulfur cluster, which participates in the redox reactions

c) The Fe protein is irreversibly inactivated by O2 while MoFe protein is activated by O2

d) MoFe protein has four subunits, each subunit has two Mo–Fe–S clusters

e) Ferredoxin serves as an electron donor to the Fe protein, and Fe protein reduces the MoFe protein without any hydrolysing ATP

f) Only prokaryotes have nitrogenase enzyme

Which of the following characteristics of nitrogenase enzyme complex is incorrect?

#Question id: 10288

#Unit 6. System Physiology – Plant

 If all the ATP are radiolabelled in the cytosol, then predict about radioactivity of each compound.

 a) All enzyme  of glycolysis will be radiolabelled except 2-phophoglycerate and phosphenol pyruvate

 b) 2-phophoglycerate and phosphenol pyruvate are radiolabelled only the next cycle of glycolysis after cytosolic ATP radiolabelling

 c) 1,3 bisphosphoglycerate will be radiolabelled at 1 and 3 both position

 d) 2-phosphoglycerate are not radiolabelled because its enzyme phosphoglycerate mutase active site contain histidine residue exchange phosphate group from 3-phosphoglycerate

 which prediction about radiolabelling is incorrect?

#Question id: 10287

#Unit 6. System Physiology – Plant

Glyceraldehyde 3-phosphate dehydrogenase avtive site contain

#Question id: 10286

#Unit 6. System Physiology – Plant

The enzyme aldolase, catalyzes a reversible aldol condensation, Fructose 1,6-bisphosphate is cleaved to yield two different triose phosphates, glyceraldehyde 3-phosphate, an aldose, and dihydroxyacetone phosphate, a ketose. There are two classes of aldolases such as;

A) Class I aldolases

B) Class II aldolases

i) Found in animals and plants

ii) Found in in fungi and bacteria

iii) formation of protonated Schiff base on enzyme and its active site contain lysine residue

iv) do not form the Schiff base intermediate and a zinc ion at the active site is coordinated with the carbonyl oxygen at C-2

In which of the following option is the given enzyme with its correct statements?

#Question id: 10285

#Unit 6. System Physiology – Plant

Some of the statements given shows the activity of PFK-1 and PFK-2, which of the following statements incorrectly shown these enzyme activity?

#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;

#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?