Questions and answers for exam Preparation

MCQs

Total Questions : 193 | Page 12 of 20 pages

Question 111. Which of the following enzymes catalyze the ADP-ribosylation of key cellular enzymes or proteins?

Diphteria toxin and cholera toxin
Dinitrogenase reductase
Protein phosphatases
Kinase

Discuss Question

Answer: Option A. -> Diphteria toxin and cholera toxin
Answer: (a).Diphteria toxin and cholera toxin

Question 112. The attachment of phosphoryl groups to specific amino acid residues is catalyzed by ___________

Diphteria toxin and cholera toxin
Dinitrogenase reductase
Protein phosphatases
Protein kinases

Discuss Question

Answer: Option D. -> Protein kinases
Answer: (d).Protein kinases

Question 113. Removal of phosphoryl groups is catalyzed by ___________

Diphteria toxin and cholera toxin
Dinitrogenase reductase
Protein phosphatases
Protein kinases

Discuss Question

Answer: Option C. -> Protein phosphatases
Answer: (c).Protein phosphatases

Question 114. Which of the following takes place due to phosphorylation of isocitrate dehydrogenase?

Inhibits the binding of citrate at active site
Degrades the enzyme
Enhances the substrate-binding affinity
No reaction

Discuss Question

Answer: Option A. -> Inhibits the binding of citrate at active site
Answer: (a).Inhibits the binding of citrate at active site

Question 115. Which of the following is false about the following reaction?
Phosphorylase a + 2H₂O → phosphorylase b + 2Pᵢ

Phosphorylase a is less active and phosphorylase b is more active
Glycogen phosphorylase catalyzes this reaction
Phosphorylase b can be transformed back into phosphorylase a by phosphorylase kinase
Phosphorylase kinase catalyzes the transfer of phosphoryl groups from ATP to Phosphorylase b

Discuss Question

Answer: Option A. -> Phosphorylase a is less active and phosphorylase b is more active
Answer: (a).Phosphorylase a is less active and phosphorylase b is more active

Question 116. Which of the following enzyme catalyzes a reaction that introduces reduced nitrogen ito cellular metabolism?

Bacterial glutamine synthase
Bacterial dinitrogenase reductase
Bacterial dinitrogenase oxidase
Phosphatase

Discuss Question

Answer: Option A. -> Bacterial glutamine synthase
Answer: (a).Bacterial glutamine synthase

Question 117. Which of the following is false about feedback regulation?

It is a type of enzymatic activity regulation
The synthesis of concerned enzyme is inhibited by interfering with the gene of that enzyme
Concentration of enzyme is reduced by the end product
The best example is the biosynthesis of L-isoleucine from L-threonine in bacteria

Discuss Question

Answer: Option D. -> The best example is the biosynthesis of L-isoleucine from L-threonine in bacteria
Answer: (d).The best example is the biosynthesis of L-isoleucine from L-threonine in bacteria

Question 118. Anthrone method is preferred in the determination of ___________