enzyme

An allosteric enzyme is generally inhibited by:

• initial substrate of the pathway

• substrate analogues

• product of the reaction catalyzed by allostreic enzyme

• product of the pathway

Answer explanation

• Allosteric enzymes are often regulated by feedback inhibition, where the product of the pathway inhibits the enzyme.

Dialysis causes:

• separation of colloids from crystalloids

• purification of colloids

• Precipitation of colloids

• none of above

Answer explanation

Dialysis is a process used to remove small molecules from a solution, which can lead to the precipitation of colloidal particles.

In enzyme kinetics, Vmax reflects

• The amount of an active enzyme

• substrate concentration

• half the substrate concentration

• enzyme substrate complex

Answer explanation

Vmax represents the maximum rate of an enzymatic reaction when the enzyme is fully saturated with the substrate, indicating enzyme availability.

Which of the following is a proteolytic enzyme?

• pepsin

• Trypsin

• Chymotrypsin

• All of these

Answer explanation

All three are proteolytic enzymes that break down proteins.

The active site of an enzyme is formed by a few of the enzymes:

• amino groups of the amino acids

• exposed sulfur bonds

• R groups of the amino acids

• carboxyl group of the amino acids

Answer explanation

The active site of an enzyme is typically formed by the R groups (side chains) of amino acids, which determine substrate specificity and catalytic activity.

The nature of an enzyme is:

• Lipid

• Vitamin

• Carbohydrate

• Protein

Answer explanation

Most enzymes are proteins, although some RNA molecules (ribozymes) also have catalytic activity.

Enzyme-driven metabolic pathways can be made more efficient by:

• grouping enzymes into multienzyme free-floating complexes

• concentrating enzymes with specific cellular compartments

• fixing enzymes into membranes so they are adjacent to each other

• All of these

Answer explanation

Grouping enzymes into complexes, localizing them to specific compartments, and fixing them to membranes all contribute to increased efficiency.

Which of the following is produced with the combination of apoenzyme and coenzyme?

• Holoenzyme

• enzymes substrate complex

• Prosthetic group

• enzyme product complex

Answer explanation

A holoenzyme consists of an apoenzyme (protein part) and a coenzyme or cofactor.

Which of the following is an extracellular enzyme?

• Catalase

• DNA polymerase

• Fibrin

• Trypsin

Answer explanation

Trypsin is secreted by the pancreas into the small intestine to aid in protein digestion.

The coenzymes have which properties?

• Having the same quaternary structure like enzymes

• structural analogues of enzymes

• soluble, colloidal, protein molecules

• Heat stable, dialyzable, non-protein organic molecules

Answer explanation

Coenzymes are small organic molecules that are heat-stable and can be separated from the enzyme.