Virtual Labs

DNA amplification by Polymerase Chain Reaction (PCR)

1. The correct order of steps in PCR is

a: Annealing, Extension, Denaturation Explanation

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b: Extension, Annealing, Denaturation Explanation

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c: Annealing, Denaturation, Extension Explanation

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d: Denaturation, Annealing, Extension Explanation

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2. A high temperature of 95ͦ C is used in PCR for the purpose of

a: Separation of the template DNA strands Explanation

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b: Synthesis of new DNA strands Explanation

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c: Binding of primers to the template Explanation

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d: All of the above Explanation

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3. How many DNA duplex is obtained from one DNA duplex after 5 cycles of PCR?

a: 8 Explanation

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b: 16 Explanation

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c: 32 Explanation

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d: 64 Explanation

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4. DNA amplification due to PCR can be analyzed using

a: SDS PAGE Explanation

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b: Agarose gel electrophoresis Explanation

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c: EMSA Explanation

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d: Isoelectric focusing Explanation

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5. Which of the following ions functions as a cofactor for DNA polymerases?

a: Mg²⁺ Explanation

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b: Zn²⁺ Explanation

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c: Cl^- Explanation

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d: Na⁺ Explanation

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6. Which of the following statements are true regarding PCR?

a: Primer extension occurs at 72°C Explanation

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b: Denaturation involves heating at 90 to 98°C Explanation

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c: Annealing involves the binding of primer between 40 to 60°C Explanation

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d: All of the above Explanation

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7. What would be the effect on the PCR reaction if any of the following circumstances arose: 1) there are no primers in the reaction, 2) there are no dNTPs in the reaction, 3) there is no Taq polymerase in the reaction?

a: PCR would proceed normally Explanation

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b: Non-specific amplification of PCR Explanation

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c: Reaction will cease after a few cycle Explanation

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d: PCR reaction would not commence Explanation

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8. Which of the following statement is true?

a: PCR require the target DNA, two primers, four dNTPs and a thermostable DNA polymerase Explanation

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b: PCR require the target DNA, one primer, four dNTPs and a thermostable DNA polymerase Explanation

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c: PCR require the target DNA, two primers, three dNTPs and a thermostable DNA polymerase Explanation

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d: PCR require the target DNA, two primers, one out of four dNTPs and a thermostable DNA polymerase Explanation

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9. During the annealing step of PCR, which of the following events occur?

a: Primer binds to their target sequence Explanation

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b: DNA polymerase extends 3′ end of primers, complementary to the template Explanation

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c: Template DNA strands separate Explanation

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d: None of the above Explanation

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10. Extension temperature of 72°C in PCR is used for the purpose of?

a: Disrupting Hydrogen bonds between complementary bases of the template DNA Explanation

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b: Annealing of primer to the template Explanation

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c: It is the optimum temperature for the action of DNA polymerases to extend the 3′ end of primers, complementary to the template Explanation

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d: None of the above Explanation

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