Enzyme Regulation: Master Enzyme Control in Biochemistry

Question 1

Which characteristic is unique to allosteric regulation of enzymes?

Accepted Answer

An effector molecule binds to a specific site on the enzyme, influencing its activity.

Answer

An inhibitor molecule binds to the enzyme's active site, blocking substrate binding.

Answer

A chemical group is added to or removed from the enzyme, altering its catalytic activity.

Answer

Gene expression is altered, affecting the production of the enzyme.

Question 2

Allosteric enzymes are regulated by:

Accepted Answer

Binding of effectors

Answer

Changes in temperature

Answer

Proteolytic cleavage

Answer

pH changes

Question 3

Which of the following covalent modifications can activate an enzyme?

Accepted Answer

Phosphorylation

Answer

Dephosphorylation

Answer

Ubiquitination

Answer

Methylation

Question 4

Which of the following is not a recognized mechanism of enzyme regulation?

Accepted Answer

pH regulation

Answer

Allosteric regulation

Answer

Covalent modification

Answer

Genetic regulation

Question 5

What is the primary role of allosteric regulators?

Accepted Answer

To bind to a specific site on the enzyme and alter its conformation

Answer

To bind to the active site and block substrate binding

Answer

To covalently modify the enzyme and alter its activity

Answer

To induce gene expression and increase enzyme production

Question 6

How does gene expression regulate enzyme activity?

Accepted Answer

By increasing or decreasing the production of the enzyme

Answer

By altering the structure of the enzyme

Answer

By changing the substrate specificity of the enzyme

Answer

By inhibiting the catalytic activity of the enzyme

Question 7

Which of the following is an example of feedback inhibition?

Accepted Answer

The end product of a metabolic pathway inhibits an early enzyme in the pathway

Answer

An allosteric regulator binds to an enzyme and increases its activity

Answer

A covalent modification activates an enzyme

Answer

Gene expression is induced to produce more of an enzyme

Question 8

How does allosteric regulation contribute to metabolic channeling?

Accepted Answer

By directing metabolites to specific enzymes within multi-enzyme complexes

Answer

By increasing the affinity of enzymes for their substrates

Answer

By inhibiting competing enzyme activities

Answer

By increasing the rate of enzyme synthesis

Question 9

Which of the following is not a type of allosteric regulation?

Accepted Answer

Competitive

Answer

Homotropic

Answer

Heterotropic

Answer

Non-competitive

Question 10

Which factor is crucial in determining enzyme-substrate interaction specificity?

Accepted Answer

Active site shape and charge

Answer

Cofactor or coenzyme presence

Answer

Substrate concentration

Answer

Temperature

Question 11

Which characteristic is specific to competitive inhibitors?

Accepted Answer

Binding to the enzyme's substrate binding site

Answer

Increasing the enzyme's Vmax

Answer

Only binding to the enzyme when the substrate is bound

Answer

Being typically irreversible inhibitors

Question 12

Proteolytic enzymes are commonly regulated through:

Accepted Answer

Zymogen activation

Answer

Phosphorylation

Answer

Allosteric regulation

Answer

Competitive inhibition

Question 13

Which of the following is NOT a type of allosteric regulation in enzymes?

Accepted Answer

Competitive

Answer

Non-competitive

Answer

Uncompetitive

Answer

Mixed-type

Question 14

The Michaelis-Menten constant (Km) represents the:

Accepted Answer

Substrate concentration at which the reaction rate is half-maximal

Answer

Maximum reaction rate

Answer

Enzyme concentration

Answer

Substrate affinity

Question 15

Feedback inhibition is a type of enzyme regulation that:

Accepted Answer

Is caused by the end product of a pathway

Answer

Inhibits the first enzyme in a metabolic pathway

Answer

Increases enzyme activity

Answer

Is irreversible

Question 16

Which of the following is not a recognized type of enzyme regulation?

Accepted Answer

Structural modification

Answer

Gene expression

Answer

Allosteric regulation

Answer

Covalent modification

Question 17

The Michaelis constant (Km) represents the substrate concentration at:

Accepted Answer

Half-maximal velocity

Answer

Substrate concentration at zero velocity

Answer

Inhibitor concentration that reduces enzyme velocity by 50%

Answer

Maximum velocity of the enzyme

Question 18

Which of the following factors can influence enzyme activity?

Accepted Answer

Temperature, pH, and substrate concentration

Answer

Inhibitor concentration only

Answer

Enzyme concentration only

Answer

Cofactor concentration only

Question 19

Enzyme regulation is important because it enables cells to:

Accepted Answer

Control metabolic pathways and respond to changes in the environment

Answer

Decrease the specificity of enzymes

Answer

Increase the rate of all biochemical reactions

Question 20

Which regulatory mechanism involves the end-product of a metabolic pathway inhibiting an enzyme earlier in the pathway?

Accepted Answer

Feedback inhibition

Answer

Substrate induction

Answer

Positive cooperativity

Answer

Feedforward activation

Question 21

During gene expression, transcription factors bind to a specific DNA region to initiate transcription. What is this region called?

Accepted Answer

Promoter

Answer

Enhancer

Answer

Silencer

Answer

Intron

Question 22

Which enzyme is primarily responsible for the phosphorylation of proteins, a key covalent modification in enzyme regulation?

Accepted Answer

Protein kinase

Answer

Isomerase

Answer

Protein phosphatase

Answer

Protease

Question 23

Allosteric enzymes often exhibit a sigmoidal curve on a Michaelis-Menten plot. What does this sigmoidal shape signify?

Accepted Answer

Cooperative binding of substrate

Answer

Constant enzyme activity

Answer

First-order reaction kinetics

Answer

Non-cooperative substrate binding

Question 24

Which of the following is NOT a mechanism of gene expression regulation?

Accepted Answer

Post-translational modification

Answer

RNA interference

Answer

Chromatin remodelling

Answer

Transcriptional regulation

Question 25

A competitive inhibitor binds to an enzyme's active site, blocking substrate binding. What effect does this have on the enzyme's Michaelis constant (K_m)?

Accepted Answer

Increases K_m

Answer

Changes K_m unpredictably

Answer

No effect on K_m

Answer

Decreases K_m

Question 26

What is a potential drawback of using allosteric inhibitors as drugs?

Accepted Answer

Off-target effects due to binding to unintended allosteric sites

Answer

High cost of synthesis

Answer

Rapid metabolism and short duration of action

Answer

Limited bioavailability

Question 27

What key advantage do covalent inhibitors have over competitive inhibitors in enzyme regulation?

Accepted Answer

Irreversible binding leading to prolonged enzyme inhibition

Answer

Lower binding affinity

Answer

Greater selectivity for the target enzyme

Answer

Increased susceptibility to enzymatic degradation