Selected MCQ

Current Question
DNA microarray analysis is used to:
  • A. Sequence whole genomes quickly
  • B. Measure expression levels of thousands of genes simultaneously
  • C. Detect protein-protein interactions
  • D. Separate DNA fragments by size
Correct Answer: B
Explanation:
DNA microarrays contain thousands of gene-specific probes. Labeled cDNA from a sample hybridizes to the array to quantify the expression of many genes in parallel.
Related Question 1
Which plasmid-based technique is used to enrich and detect low-abundance mRNAs by reverse transcription into cDNA?
  • A. RFLP analysis
  • B. Northern blotting
  • C. RT-PCR (reverse-transcription PCR)
  • D. Affinity chromatography
Correct Answer: C
Explanation:
RT-PCR involves reverse-transcribing RNA to cDNA and then amplifying specific sequences by PCR. It is very sensitive for detecting low-abundance transcripts.
Related Question 2
Fluorescence in situ hybridization (FISH) is a technique used to:
  • A. Fragment DNA into smaller pieces
  • B. Visualize specific DNA or RNA sequences in cells or chromosomes using fluorescent probes
  • C. Measure protein concentration in solution
  • D. Separate DNA by size
Correct Answer: B
Explanation:
FISH uses fluorescently labeled probes that hybridize to specific DNA sequences on chromosomes or cells, allowing localization under a fluorescence microscope.
Related Question 3
In Southern blotting, what type of probe is used to detect specific DNA sequences?
  • A. DNA probe labeled with a reporter
  • B. RNA probe labeled with a reporter
  • C. Protein probe labeled with antibody
  • D. Carbohydrate probe
Correct Answer: A
Explanation:
Southern blot uses a labeled single-stranded DNA (or RNA) probe complementary to the target DNA sequence, hybridizing to it on the membrane.
Related Question 4
Enzyme-linked immunosorbent assay (ELISA) is primarily used to:
  • A. Measure DNA concentration
  • B. Detect specific proteins or antibodies by an enzyme-mediated color change
  • C. Visualize chromosomes under a microscope
  • D. Amplify RNA
Correct Answer: B
Explanation:
ELISA employs enzyme-linked antibodies. When the target antigen or antibody is present, a substrate is converted to a colored product, indicating a positive result.