Enzymology - Part I - Quiz, Trivia & Questions

2.

Select the mismatched pair regarding enzymes and co-factor

Manganese - isocitrate dehydrogenase
Copper - cytochrome oxidase
Zinc - Carbonic anhydrase
Cobalt - vitamin B12
Selenium - glutathione peroxidase
Molybdenum - xanthine oxidase
All are correctly matched.

Correct Answer

A. All are correctly matched.

Explanation

The given answer states that all the pairs regarding enzymes and co-factors are correctly matched. This means that each enzyme listed is indeed associated with the corresponding co-factor mentioned.

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3.

False regarding Km

Km = concentration of substrate at ½ Vmax
Km is inversely proportional to the affinity
Km is increased in non-competitive inhibition.
Km is increased in competitive inhibition.

Correct Answer

A. Km is increased in non-competitive inhibition.

Explanation

Km, or the Michaelis constant, represents the substrate concentration at which the reaction rate is half of Vmax (the maximum velocity). It is a measure of the affinity of the enzyme for its substrate; a lower Km indicates higher affinity, and a higher Km indicates lower affinity.
A) Km = concentration of substrate at ½ Vmax: This is true and is the definition of Km.
B) Km is inversely proportional to the affinity: This is true. A lower Km means higher affinity, and a higher Km means lower affinity.
C) Km is increased in non-competitive inhibition: This is false. In non-competitive inhibition, the Km remains unchanged because the inhibitor affects the enzyme's activity but does not compete with the substrate for the active site.
D) Km is increased in competitive inhibition: This is true. In competitive inhibition, the Km increases because the inhibitor competes with the substrate for the active site, making it appear as though the enzyme has a lower affinity for the substrate.

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0

4.

Select the Serine protease(s)

Chymotrypsin
Trypsin
Elastase
Thrombin
All of the above

Correct Answer

A. All of the above

Explanation

Serine Protease contain serine at their active site which is a part of catalytic triad.

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2

5.

Which is an enzyme with low specificity ?

Glucokinase
Tyrosinase
Hexokinase
None of the above

Correct Answer

A. Hexokinase

Explanation

Hexokinase is an enzyme with low specificity because it can phosphorylate a wide range of hexoses, such as glucose, mannose, and fructose. It does not require a specific substrate and can catalyze the phosphorylation of multiple hexose sugars. In contrast, enzymes with high specificity only work on specific substrates and have a narrow range of substrates they can act upon.

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6.

False regarding Lineweaver-Burk plot

1/Vo is plotted against 1/[S]
1/[S] is plotted against 1/Vo
Km and Vmax can be found.
Mechanism of action of enzyme inhibitors can be found

Correct Answer

A. 1/[S] is plotted against 1/Vo

Explanation

also called dobule reciprocal (1/vo Vs 1/[S]) |
straight line is obtained |
intercept on x-axis is equal to -1/Km & intercept on the y-axis is equal to 1/Vmax.

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7.

Chemical nature of enzyme

Proteins
RNA
Both
None

Correct Answer

A. Both

Explanation

Enzymes are biological catalysts that speed up chemical reactions in living organisms. They can be either proteins or RNA molecules, depending on the specific enzyme. Some enzymes are made up of proteins, while others are made up of RNA. Therefore, the correct answer is "Both" because enzymes can have a chemical nature of either proteins or RNA.

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1

Enzymology - Part I

In the graph shown below, increasing the substrate concentration does not increase the rate of reaction at a certain point because

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Select the mismatched pair regarding enzymes and co-factor

False regarding Km

Select the Serine protease(s)

Which is an enzyme with low specificity ?

False regarding Lineweaver-Burk plot

Chemical nature of enzyme