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Using the controls in the previous questions 8 - 10, you have specific primers available to detect and amplify a fragment from HIV’s reverse transcriptase gene (RT) and a fragment from the human B-actin gene (this gene is found in all human genomic DNA). You set up 4 tubes for PCR [Positive control (A), Negative control (B), No Template Control (C), and the unknown patient DNA (D)] and you run the products on a gel. The migration of the RT and B-actin PCR products is shown in the lane to the left of the ladder in the diagram below.

Question 11 (2 points)

Which of the following images represents what the results should be in lane A, the positive control?

Question 11 options:

RT and B-actin bands

B-actin band

no bands

RT band

View hint for Question 11
Question 12 (2 points)

Which of the following images represents what the results should be in lane B, the negative control?

Question 12 options:

B-actin band

RT band

RT band, B-actin band

no bands

View hint for Question 12
Question 13 (2 points)

Which of the following images represents what the results should be in lane C, the NTC?

Question 13 options:

RT band, B-actin band

RT band

B-actin band

no bands

View hint for Question 13
Question 14 (2 points)

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Which of the following images represents what the results should be in lane D, the patient sample IF the patient is infected with HIV?

Question 14 options:

b-Actin band

RT band and b-actin band

RT band

no bands

View hint for Question 14
Page 4 of 4

10 of 14 qu

1 answer

To answer your questions regarding the PCR results based on typical expectations for a positive control, negative control, no template control, and an unknown patient sample, let's analyze each lane:

Question 11: Positive Control (Lane A)

  • Expected Result: Since this lane contains both the primers for the HIV reverse transcriptase (RT) gene and the human B-actin gene, you should expect to see bands for both genes.
  • Correct Answer: RT and B-actin bands

Question 12: Negative Control (Lane B)

  • Expected Result: The negative control should contain no template DNA, so there should be no amplification. Therefore, no bands should be visible.
  • Correct Answer: no bands

Question 13: No Template Control (Lane C)

  • Expected Result: Similar to the negative control, the no template control should not have any template DNA, leading to no amplification. Thus, you should see no bands.
  • Correct Answer: no bands

Question 14: Patient Sample (Lane D) if infected with HIV

  • Expected Result: If the patient is infected with HIV, you should expect to see the band for the RT gene (since the target is present in the patient sample) as well as a band for the B-actin gene (which is always present in human samples).
  • Correct Answer: RT band and B-actin band

These answers reflect the expectations based on standard PCR results and controls used in molecular biology.