Virtual Labs

Enzyme-linked immunosorbent assay (ELISA) using protein and antibody

1. What is the primary characteristic of Direct ELISA?

a: Utilizes two labeled antibodies Explanation

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b: Involves a competitive reaction Explanation

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c: Antigen or antibody is immobilized directly Explanation

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d: Uses DNA technology for detection Explanation

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2. What is the purpose of the substrate in an ELISA test?

a: To produce a colored or fluorescent signal Explanation

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b: To amplify the signal Explanation

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c: To detect the antigen or antibody Explanation

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d: To remove unwanted molecules Explanation

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3. Which ELISA type is most suitable for quantitative analysis of antigens with high specificity?

a: Indirect ELISA Explanation

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b: Competitive ELISA Explanation

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c: Sandwich ELISA Explanation

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d: Open Sandwich ELISA Explanation

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4. Which of the following is not a principle of ELISA (Enzyme-Linked Immunosorbent Assay)?

a: Specific antigen-antibody binding Explanation

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b: Use of an enzyme-conjugated secondary antibody Explanation

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c: Detection of a chromogenic or fluorescent signal Explanation

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d: Separation of unbound components by size exclusion chromatography Explanation

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5. Arrange the following steps about ELISA in correct order :
i) incubate with antibody-enzyme complex that binds primary antibody
ii) coat surface with antigen, block unoccupied sites with nonspecific protein
iii) add substrate, formation of colored product indicates presence of specific antigen
iv) incubate with primary antibody against specific antigen

a: i, iv, ii, iii Explanation

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b: i, iv, iii, ii Explanation

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c: ii, iv, iii, i Explanation

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d: ii, iv, i, iii Explanation

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6. What is the key feature of competitive ELISA?

a: Two antibodies recognizing different epitopes are used Explanation

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b: Competition between labeled and sample antigen for binding sites Explanation

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c: Detection involves DNA technology Explanation

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d: Involves direct binding of antigens and antibodies Explanation

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7. What is the primary purpose of the coating step in the ELISA process?

a: To block non-specific binding Explanation

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b: To immobilize an antigen or antibody on a solid surface Explanation

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c: To detect the presence of an enzyme Explanation

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d: To wash away unbound substances Explanation

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8. In the detection phase of ELISA, what is typically added to the wells to bind to the antigen?

a: A blocking buffer Explanation

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b: A chromogenic substrate Explanation

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c: A detection antibody conjugated with an enzyme Explanation

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d: A capture antibody Explanation

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9. What is the purpose of the enzyme-substrate reaction in ELISA?

a: To immobilize the antigen Explanation

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b: To produce a detectable signal Explanation

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c: To block non-specific binding Explanation

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d: To coat the plate with antibodies Explanation

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10. Which disease is NOT commonly diagnosed using ELISA?

a: HIV Explanation

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b: Syphilis Explanation

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c: Influenza Explanation

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d: Hypertension Explanation

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