B.Pharm. Bachelor of Pharmacy Bachelor of Pharmacy (B.Pharm.) Biochemistry 5

Question 1

Which amino acid is the primary precursor for gluconeogenesis released from skeletal muscle during fasting?

Accepted Answer

Alanine

Answer

Alanine carries amino groups from muscle to the liver via the glucose-alanine cycle and serves as a key gluconeogenic precursor during fasting.

Question 2

What is the function of signal peptides on newly synthesized proteins destined for the endoplasmic reticulum?

Accepted Answer

They direct the ribosome-protein complex to the ER membrane for co-translational insertion

Answer

Signal peptides (N-terminal hydrophobic sequences) are recognized by the signal recognition particle (SRP), which docks the ribosome on the ER membrane.

Question 3

Glucagon stimulates glycogen breakdown in the liver primarily by activating which cascade?

Accepted Answer

Adenylyl cyclase → cAMP → PKA → phosphorylase kinase → glycogen phosphorylase

Answer

Glucagon binds its GPCR, activating adenylyl cyclase to raise cAMP, which activates PKA; PKA phosphorylates and activates glycogen phosphorylase via phosphorylase kinase.

Question 4

Which of the following statements about enzyme active sites is correct?

Accepted Answer

They are complementary in shape and charge to the transition state of the reaction

Answer

Enzymes are best complementary to the transition state (not the substrate or product), which lowers the activation energy and stabilizes the highest-energy intermediate.

Question 5

Biotin-dependent carboxylase reactions share which mechanistic feature?

Accepted Answer

They use ATP to fix CO2 onto a biotin-enzyme intermediate before transferring it to substrate

Answer

Biotin carboxylases use ATP to carboxylate the biotin cofactor, forming carboxybiotin, which then transfers the carboxyl group to the acceptor substrate.

B.Pharm. Bachelor of Pharmacy Practice Test

B.Pharm. Bachelor of Pharmacy Practice Test

B.Pharm. Bachelor of Pharmacy Bachelor of Pharmacy (B.Pharm.) Biochemistry 5