Selected MCQ

Current Question
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 1
In genomic imprinting, the expression of a gene depends on its parental origin. For example, only the paternally inherited allele of a certain gene is expressed. This is known as:
  • A. Epigenetic modification
  • B. Loss of heterozygosity
  • C. Imprinting
  • D. Mendelian inheritance
Correct Answer: C
Explanation:
Genomic imprinting is an epigenetic phenomenon where only one allele (maternal or paternal) is expressed, depending on the parent of origin, while the other is silenced.
Related Question 2
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 3
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 4
Which of the following is NOT typically controlled during industrial fermentation in a bioreactor?
  • A. Temperature
  • B. pH
  • C. Oxygen concentration
  • D. DNA sequence of the microorganism
Correct Answer: D
Explanation:
A, B, and C (temperature, pH, oxygen) are critical parameters controlled in fermentation. The chosen strain fixes the DNA sequence and is not a controlled parameter during the run.
Related Question 5
During agarose gel electrophoresis of DNA, in which direction do DNA fragments migrate?
  • A. Toward the cathode (negative electrode)
  • B. Toward the anode (positive electrode)
  • C. DNA does not migrate in agarose
  • D. Toward the North Pole
Correct Answer: B
Explanation:
DNA has a negative charge (due to phosphate groups) and migrates toward the positively charged electrode (anode) when an electric field is applied.