Selected MCQ

Current Question
In gene therapy using a viral vector, what is a major concern related to using retroviruses?
  • A. They cannot infect human cells
  • B. They only integrate into mitochondrial DNA
  • C. Insertional mutagenesis by random integration into the host genome
  • D. They cannot carry large genes
Correct Answer: C
Explanation:
Retroviral vectors integrate randomly into the host genome, risking insertional mutagenesis (disrupting host genes), which can cause cancer or other issues.
Related Question 1
Which viral vector carries a high risk of insertional mutagenesis due to genome integration?
  • A. Adenoviral vector
  • B. Retroviral vector
  • C. Adeno-associated viral vector
  • D. Liposome-based vector
Correct Answer: B
Explanation:
Retroviruses integrate their genome into the host DNA. This random insertion can disrupt host genes, increasing the risk of mutagenesis (used with caution in gene therapy).
Related Question 2
In a cloning vector, what is the purpose of including an antibiotic resistance gene?
  • A. To replicate the plasmid in host cells
  • B. As a selectable marker to identify transformed cells
  • C. To transcribe the cloned gene at high levels
  • D. To initiate DNA replication
Correct Answer: B
Explanation:
The antibiotic resistance gene allows selection: only bacteria that have taken up the plasmid (and express resistance) will grow on antibiotic-containing media.
Related Question 3
Alternative splicing occurs during gene expression at the level of:
  • A. DNA replication
  • B. Transcription initiation
  • C. Pre-mRNA processing (RNA splicing)
  • D. Protein folding
Correct Answer: C
Explanation:
Alternative splicing of pre-mRNA allows different exons to be joined or skipped, producing multiple mRNA variants from one gene during RNA processing.
Related Question 4
Which term describes genes that are located on the same chromosome and inherited together more often than by chance?
  • A. Linked genes
  • B. Epistatic genes
  • C. Polygenic genes
  • D. Independent genes
Correct Answer: A
Explanation:
Linked genes are near each other on the same chromosome. They tend to be inherited together, and their recombination frequency is less than 50%.
Related Question 5
Which chromatography technique separates proteins primarily based on size using a gel matrix?
  • A. Ion-exchange chromatography
  • B. Gel filtration (size-exclusion) chromatography
  • C. Affinity chromatography
  • D. Reverse-phase chromatography
Correct Answer: B
Explanation:
Gel filtration chromatography (size-exclusion) separates proteins by size: larger molecules elute first because they enter fewer pores in the matrix, while smaller molecules elute later.