Quiz on Enzyme Inhibition

Certain chemicals or factors inhibit or reduce the activities of enzyme. They are called enzyme inhibitors. Enzyme action can be inhibited in four different ways: a) competitive inhibition b) Non competitive inhibition c) Allosteric inhibition or feed back inhibition and d) Denaturation of enzymes.
Enzyme inhibition caused by a substance resembling substrate molecule through blocking its active site is competitive inhibition. Non competitive inhibition occurs when the inhibitory chemical, which does not have to resemble the substrate, binds to the enzyme other than at the active site. Feed back inhibition is the most common allosteric modulation. When the end products accumulate in the cell after enzymatic activity, they inhibit their own production. Due to denaturation, the molecular confirmation of the enzyme molecule will be lost there by they are inhibited. 
1. Competitive inhibition is
always reversible
always irreversible
sometimes reversible
none of these
2. Which is a typical example of feedback inhibition?
cyanide and cytochrome reaction
sulpha drugs and folic acid synthesizer bacteria
allosteric inhibition of hexokinase by glucose 6 phosphate
reaction between suucinic dehydrogenase and succinic acid
3. Which one of the following statements regarding enzyme inhibition is correct?
competitive inhibition is seen a substrate competes with an enzyme for binding to an inhibitor protein
non competitve inhibition of an enzyme can be overcome by adding large amount of substrate.
competitive inhibition is when the substrate and the inhibitor compete for the active site on the enzyme
competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme.
4. Which of the following is/ are irreversible?
competitive inhibition
Non competitive inhibition
Allosteric inhibition
None of these
5. Which of the following is an example for irreversible inhibitor
Iodoacetamide, a cys residue modifier at the active sites
Di-isopropylphosphofluoridate (DIPF) with the enzyme acetylcholineesterase, involved in nerve impulse transmission
Penicillin with glycopeptides transpeptidase enzyme involved in bacterial cell wall synthesis
all of these
6. The inhibition caused by the final end product of a reaction is called
Non competitive inhibition
competitive inhibition
Allosteric inhibition
All of these
7. Which of the following are allosteric enzymes
RUBISCO
PEP Carboxylase
Phosphofructokinase
All of these
8. The competitive inhibitor malonic acid resembles
malic acid
fumaric acid
succinic acid
oxaloacetate acid
9. Competitive inhibition overcome by adding substrate show that
enzymes are pH dependent
enzymes are made up of protein
enzyme are biocatalysts
enzymes are specific in nature
10. Inhibition of enzyme cytochrome oxidase by carbon monoxide is an example for
Feed back inhibition
competitive inhibition
Non competitive inhibition
None of the above
Score =
Correct answers:

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