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Chapter 6: Clinical Practice: Molecular Pathology

Nucleic acid probe assays can be used to detect, measure, or characterize particular nucleic acids. These assays rely on which of the following principles?

A. DNA differs in every cell of a particular individual.

B. A probe hybridizes to its complementary sequence.

C. Probes bind to double-stranded DNA and not to RNA.

D. RNA is converted to DNA using an enzyme derived from geysers.

E. Heat or high pH converts single-stranded to double-stranded DNA.

Answer: B

Explanation: A single-stranded “nucleic acid probe” is designed to find a particular gene locus based on its ability to hybridize to a complementary sequence of nucleotides (e.g., A complements T, G complements C).

Which of the following best describes the purpose of PCR?

A. Copy a DNA segment.

B. Heat DNA to nearly boiling.

C. Create a standard curve.

D. Find an amino acid substitution.

E. Diagnose autoimmune disease.

Answer: A

Explanation: PCR is among the most useful technologies applied in clinical molecular laboratories because it copies a designated segment of DNA thousands to millions of times, facilitating downstream efforts to detect, quantify, or further analyze the amplified DNA for variants.

Which of the following reagents is most critical for making a PCR assay specific for human as opposed to infectious organism targets?

A. Ions

B. Water

C. Primers

D. DNA polymerase

E. Deoxyribonucleotides

Answer: C

Explanation: Primers are short probes that hybridize to the either end of the segment of DNA to be copied during a PCR assay. They are called “primers” because once bound they alert the DNA polymerase enzyme where to start copying a DNA strand, thus conferring sequence specificity to the reaction.

In situ hybridization is best used to:

A. Localize TP53 protein in a tissue section.

B. Detect heritable HFE C282Y mutation.

C. Localize Epstein-Barr virus in cancer tissue.

D. Match a suspect ...

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