Enzymology - Part I

By Kar
Kar, Assistant Professor (Biochemistry)
Karthikeyan Pethusamy is an assistant professor in the Department of Biochemistry at the All India Institute of Medical Sciences in New Delhi
Quizzes Created: 33 | Total Attempts: 44,155
, Assistant Professor (Biochemistry)
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Enzymology -  Part I - Quiz

Test your knowledge and understanding ! May be Little tough to answer. . . . .


Questions and Answers
  • 1. 

    Select the Serine protease(s)

    • A.

      Chymotrypsin

    • B.

      Trypsin

    • C.

      Elastase

    • D.

      Thrombin

    • E.

      All of the above

    Correct Answer
    E. 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. 

    Select the mismatched pair regarding enzymes and co-factor

    • A.

      Manganese - isocitrate dehydrogenase

    • B.

      Copper - cytochrome oxidase

    • C.

      Zinc - Carbonic anhydrase

    • D.

      Cobalt - vitamin B12

    • E.

      Selenium - glutathione peroxidase

    • F.

      Molybdenum - xanthine oxidase

    • G.

      All are correctly matched.

    Correct Answer
    G. 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. 

    Which is an enzyme with low specificity ?

    • A.

      Glucokinase

    • B.

      Tyrosinase

    • C.

      Hexokinase

    • D.

      None of the above

    Correct Answer
    C. 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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  • 4. 

    False regarding Km

    • A.

      Km = concentration of substrate at ½ Vmax

    • B.

      Km is inversely proportional to the affinity

    • C.

      Km is increased in non-competitive inhibition.

    • D.

      Km is increased in competitive inhibition.

    Correct Answer
    C. Km is increased in non-competitive inhibition.
    Explanation
    As the inhibitor competes for the active site in competitive inhibition, more substrate is needed to overcome the inhibition. So, Km increases.

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  • 5. 

    False regarding Lineweaver-Burk plot

    • A.

      1/Vo is plotted against 1/[S]

    • B.

      1/[S] is plotted against 1/Vo

    • C.

      Km and Vmax can be found.

    • D.

      Mechanism of action of enzyme inhibitors can be found

    Correct Answer
    B. 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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  • 6. 

    Chemical nature of enzyme

    • A.

      Proteins

    • B.

      RNA

    • C.

      Both

    • D.

      None

    Correct Answer
    C. 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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  • 7. 

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

    • A.

      All of the enzymes are occupied by substrates

    • B.

      All of the enzymes have been denatured

    • C.

      Both are correct

    • D.

      None are correct

    Correct Answer
    A. All of the enzymes are occupied by substrates
    Explanation
    Increasing the substrate concentration does not increase the rate of reaction at a certain point because all of the enzymes are already occupied by substrates. This means that there are no free enzymes available to bind with additional substrates and catalyze the reaction at a faster rate. Once all the enzymes are occupied, the reaction rate reaches a maximum and cannot be further increased by increasing the substrate concentration.

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Kar |Assistant Professor (Biochemistry) |
Karthikeyan Pethusamy is an assistant professor in the Department of Biochemistry at the All India Institute of Medical Sciences in New Delhi

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  • Mar 21, 2023
    Quiz Edited by
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    Kar
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