Q-1. Proteins targeted for destruction in eukaryotes are covalently linked to
a) Clathrin
b) Pepsin
c) Laminin
d) Ubiquitin
Answer: Ubiquitin
Explanation:
Proteins that are defective or destined for rapid turnover are often marked for destruction by ubiquitination- the attachment of small, highly conserved protein, called Ubiquitin.
Proteins marked in this way are rapidly degraded by a cellular component known as the proteasome, which is complex, ATP-dependent, proteolytic system located in cytosol.
Q-2. Which of the following is not a rate limiting enzyme?
a) HMG CoA Reductase
b) Phospho-fructokinase
c) Acetyl CoA Carboxylase
d) Malonate dehydrogenase
Answer: Malonate dehydrogenase
Explanation:
Rate limiting enzyme:
HMG CoA Reductase: Rate limiting enzyme in cholesterol biosynthesis
Acetyl CoA Carboxylase: Rate limiting enzyme in fatty acid biosynthesis
Phospho-fructokinase: Rate limiting enzyme in glycolysis
Q-3. All of the following enzymes are regulated by calcium or calmodulin except
a) Adenylate cyclase
b) Glycogen synthase
c) Guanylyl cyclase
d) Hexokinase
Answer: Hexokinase
Explanation:
Enzymes regulated by calcium or calmodulin:
Adenylate cyclase
Guanylyl cyclase
Glycogen synthase
Pyruvate carboxylase
Pyruvate dehydrogenase
Pyruvate kinase