Genetics and Molecular Biology MCQs

354 MCQs with clinical pearls · MBBS Biochemistry · Prof Jariya

Topics covered (39)

Transcription — 23 MCQs
Translation — 20 MCQs
Genetic Terminology — 20 MCQs
Recombinant DNA Techniques — 19 MCQs
DNA Damage and Repair — 17 MCQs
Inheritance Patterns and Pedigrees — 17 MCQs
Mutations — 16 MCQs
Epigenetics — 14 MCQs
DNA Replication — 14 MCQs
Gene Regulation — Prokaryotic — 13 MCQs
Post-transcriptional Modification — 12 MCQs
Genetics Terminology and Polymorphisms — 12 MCQs
RNA Interference — 11 MCQs
Inheritance Patterns — 11 MCQs
Progeria and Lamin A — 10 MCQs
Cancer Genetics — 10 MCQs
RNA Types and Functions — 9 MCQs
Gene Mutations — 9 MCQs
Nucleic Acid Structure — 8 MCQs
Gene Therapy — 7 MCQs
Chromatin Structure — 7 MCQs
Chromosome Structure and Karyotype — 7 MCQs
Gene Regulation — Iron Metabolism — 6 MCQs
Trinucleotide Repeat Expansion — 6 MCQs
Telomeres and Telomerase — 6 MCQs
Mendelian Principles — 6 MCQs
Genetic Code and Wobble — 5 MCQs
DNA Cloning — 5 MCQs
Clinical Genetics — 5 MCQs
Polymerase Chain Reaction — 5 MCQs
Structural Chromosomal Abnormalities — 5 MCQs
Gene Regulation — Eukaryotic — 4 MCQs
Chromosomal Abnormalities — 4 MCQs
Prokaryotic Gene Regulation — 3 MCQs
Eukaryotic Gene Regulation — 2 MCQs
DNA Sequencing — 2 MCQs
Human Genome Project — 2 MCQs
Cytogenetic Techniques — 1 MCQs
RNA Surveillance — 1 MCQs

Sample MCQs with clinical pearls

A woman who is apparently healthy is found to have anti-HCV antibodies during screening for blood donation. Which of the following tests can be used to determine the HCV viral load?

A) Conventional PCR

B) Nested PCR

C) Real-time reverse-transcription PCR (RT-qPCR) ✔

D) Reverse-transcription PCR (RT-PCR)

E) Southern blotting

Anti-HCV antibody indicates EXPOSURE, not active infection - about a quarter of people clear the virus spontaneously yet keep the antibody for life. Active infection is confirmed by detecting the virus itself, and since HCV is an RNA virus this requires REAL-TIME RT-PCR: reverse transcriptase makes cDNA, then quantitative PCR measures viral load. The same assay guides and monitors treatment. MEMORY: 'Antibody says you met the virus; PCR says it is still there.'

Three individuals A, B, and C, share syringes. Person A has recently started intravenous drug use, whereas B and C are chronic drug users. Person C has clinical features of AIDS. Which of the following tests is most appropriate for detecting HIV DNA in person A?

A) ELISA

B) Immunofluorescence assay

C) Quantitative PCR (qPCR) ✔

D) Radioimmunoassay (RIA)

E) Western blotting

QUANTITATIVE PCR measures viral load in real time, with fluorescence rising as product accumulates; the cycle threshold is inversely proportional to starting template. In recent exposure, antibody tests are still negative during the WINDOW PERIOD, so only nucleic acid testing detects infection - which is why qPCR is used for early diagnosis and for screening donated blood. MEMORY: 'Before the antibody appears, only PCR can find the virus.'

Which of the following tests is most appropriate for detecting HIV DNA in person a drug chronic addict with history of syringe sharing with other addicts?

A) ELISA

B) Immunofluorescence assay

C) Quantitative PCR (qPCR) ✔

D) Radioimmunoassay (RIA)

E) Western blotting

Detecting HIV DNA requires amplification of the PROVIRAL DNA integrated into host cells, and QUANTITATIVE PCR does this directly without needing reverse transcription of viral RNA. It is the test of choice in the window period, in neonates of HIV-positive mothers - where maternal antibody crosses the placenta and confounds serology for up to 18 months - and for monitoring viral load. MEMORY: 'Maternal antibody confuses the test; the virus's own DNA does not.'

These are three of 354 MCQs in this section. Every question carries a clinical pearl explaining the reasoning.

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