Question 1

Which of the following best describes the function of an oxidoreductase enzyme?

Accepted Answer

It catalyzes oxidation-reduction reactions by transferring electrons between molecules.

Question 2

A kinase enzyme transfers a phosphate group from ATP to glucose. To which major class of enzymes does kinase belong?

Accepted Answer

Transferases

Question 3

Which of the following is NOT one of the six internationally accepted classes of enzymes?

Accepted Answer

Polymerases

Question 4

Which enzyme class is responsible for catalyzing the conversion of a cis-fatty acid into a trans-fatty acid?

Accepted Answer

Isomerases

Question 5

Which of the following is an indicator that a reaction is catalyzed by a lyase enzyme?

Accepted Answer

Loss of a functional group

Question 6

Which class of enzyme is required to combine two molecules using ATP?

Accepted Answer

Ligase

Question 7

Which enzyme class catalyzes the hydrolysis of peptide bonds in proteins?

Accepted Answer

Hydrolases

Question 8

Which of the following best describes the function of a transferase enzyme?

Accepted Answer

It catalyzes the transfer of functional groups between molecules.

Question 9

Which enzyme class is responsible for catalyzing the rearrangement of atoms within a molecule, such as the conversion of glucose-6-phosphate to fructose-6-phosphate in glycolysis?

Accepted Answer

Isomerases

Question 10

Which of the following reactions is most likely catalyzed by a hydrolase enzyme?

Accepted Answer

The cleavage of a peptide bond in a protein by the addition of water

Question 11

Which enzyme class is responsible for catalyzing the joining of two molecules, such as in DNA ligation, and typically requires energy from ATP?

Accepted Answer

Ligases

Question 12

Which of the following best describes the function of an isomerase enzyme?

Accepted Answer

It catalyzes the rearrangement of atoms within a molecule.

Question 13

Which enzyme class is responsible for catalyzing the removal of a group from a substrate without hydrolysis, often resulting in the formation of a double bond?

Accepted Answer

Lyases

Question 14

Which of the following is a real-life example of an oxidoreductase enzyme?

Accepted Answer

Lactate dehydrogenase catalyzing the conversion of pyruvate to lactate

Question 15

Which enzyme class would be most likely to catalyze the following reaction: $$ \mathrm{ATP} + \mathrm{L	ext{-}glutamate} + \mathrm{NH}_3 ightarrow \mathrm{L	ext{-}glutamine} + \mathrm{ADP} + \mathrm{P_i} $$?

Accepted Answer

Ligase

Question 16

Which enzyme class is responsible for the following reaction: $$ \mathrm{Sucrose} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{Glucose} + \mathrm{Fructose} $$?

Accepted Answer

Hydrolase

Question 17

Which enzyme class is responsible for catalyzing the transfer of an amino group from glutamate to oxaloacetate, forming aspartate and alpha-ketoglutarate?

Accepted Answer

Transferase

Question 18

Which enzyme class is responsible for catalyzing the following reaction: $$ \mathrm{Fumarate} \rightarrow \mathrm{Malate}  in $$the citric acid cycle, where water is added across a double bond?

Accepted Answer

Lyase

Question 19

Which enzyme class is responsible for catalyzing the conversion of glucose-1-phosphate to glucose-6-phosphate?

Accepted Answer

Isomerase

Question 20

Which enzyme class is responsible for catalyzing the following reaction: $$ \mathrm{Pyruvate} + \mathrm{NADH} + \mathrm{H}^+ \rightarrow \mathrm{Lactate} + \mathrm{NAD}^+ $$?

Accepted Answer

Oxidoreductase

Major Classes of Enzymes: Definitions, Functions, and Examples

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