PPCHEM M9 Q3 FINALS

Which of the following statements most accurately describes the structural and functional relationship between an apoenzyme and its cofactors?

• Apoenzyme is the inorganic ion, and cofactors are the protein parts that stabilize it.

• Apoenzyme alone is catalytically active; cofactors modulate substrate binding.

• Apoenzyme is the protein portion of an enzyme requiring cofactors (organic or inorganic) to become catalytically active.

• Cofactors are exclusively vitamins that form the enzyme’s peptide backbone.

Considering enzymatic activity, how does temperature affect enzyme structure and function above the optimal range of 35-40 °C?

• Increased temperature causes reversible conformational changes without activity loss.

• Above 65 °C with moisture, enzymes undergo irreversible denaturation, resulting in complete loss of catalytic activity.

• Enzymes become more efficient at catalysis above 65 °C due to increased kinetic energy.

• Enzymatic activity plateaus and remains stable at extreme temperatures due to compensatory ionic bonding.

Which of the following is NOT a principal classification of enzymes based on their action as per the International Union of Biochemistry system?

• Ligases – catalyze the joining of two molecules coupled with ATP cleavage.

• Hydrolases – catalyze group transfer reactions other than hydrogen atoms.

• Isomerases – catalyze geometric and optical isomer interconversions.

• Lyases – catalyze removal of groups to form double bonds without hydrolysis.

Which enzyme initiates polysaccharide digestion in humans, and how does its presence differ across animal species?

• Pancreatic amylase; present exclusively in carnivorous animals.

• Ptyalin (Salivary amylase); present in humans but absent in species like dogs and horses.

• Maltase; universally present in all animals.

• Invertase; found only in herbivores.

In enzymology, why is the enzyme papain uniquely suited for obstetric surgical applications such as episiotomy?

• It selectively coagulates milk proteins to reduce bleeding.

• It functions exclusively in acidic gastric environments to aid protein digestion.

• It is a proteolytic enzyme mixture capable of soft tissue debridement and gentle protein degradation.

• It inhibits trypsin to decrease enzymatic activity during surgery.

Enzymes like urease are widely used in laboratories to catalyze urea degradation. From which natural source is urease primarily extracted?

• Oily seeds rich in lipase

• Soybeans

• Gastric juices of mammals

• Pancreatic juice from hogs

What sets apart derived proteins (secondary derived) like peptones from primary proteins?

• They retain complete tertiary structure with no hydrolysis.

• They represent extensively hydrolyzed protein fragments with molecular weights lower than proteoses.

• They are formed only by heat denaturation without any enzymatic action.

• They contain inorganic cofactors such as metals exclusively.

How does the enzyme thrombin contribute to hemostasis?

• By hydrolyzing triglycerides into fatty acids.

• By converting fibrinogen into insoluble fibrin to form blood clots.

• By reducing oxidized cofactors in biochemical pathways.

• By catalyzing urea degradation to ammonia.

Tissue plasminogen activator (T-PA) is clinically significant. Which cell line is used for its recombinant production?

• Escherichia coli

• Chinese Hamster Ovary cells

• Bacillus subtilis

• Streptococci group C bacteria

Which conjugated protein class contains a colored prosthetic group and includes hemoglobin as an example?

• Glycoproteins

• Metalloproteins

• Chromoproteins

• Phosphoproteins