Genetic engineering involves manipulating DNA to alter organisms for research, drug development, and therapeutic applications. This concise guide covers basic principles such as recombinant DNA technology, gene cloning, plasmid and viral vectors, restriction enzymes, DNA ligases, PCR, sequencing, expression systems, codon optimization, and CRISPR–Cas systems. Emphasis is placed on laboratory techniques, selection markers, transformation/transfection methods, biosafety, and pharmaceutical applications like recombinant protein production and gene therapy. Designed for B.Pharm students, the material links theoretical concepts with practical implications in drug discovery, formulation, and biomanufacturing. Clear definitions, mechanism-focused explanations, and clinically relevant examples prepare you for applied questions and lab decision-making.
Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the best definition of genetic engineering?
- Spontaneous mutation of genes during cell division
- Deliberate modification of an organism’s genome using molecular techniques
- Natural selection acting on genetic variation
- Breeding of organisms based on phenotype
Correct Answer: Deliberate modification of an organism’s genome using molecular techniques
Q2. What does recombinant DNA (rDNA) refer to?
- DNA isolated from a single chromosome
- DNA molecules formed by joining DNA from different sources
- Genomic DNA without introns
- RNA molecules converted into DNA
Correct Answer: DNA molecules formed by joining DNA from different sources
Q3. What is the primary role of restriction enzymes in cloning?
- To synthesize DNA from an RNA template
- To cut DNA at specific recognition sequences
- To ligate DNA fragments
- To transcribe DNA into RNA
Correct Answer: To cut DNA at specific recognition sequences
Q4. DNA ligase is used in genetic engineering to:
- Denature double-stranded DNA
- Cut DNA at palindromic sites
- Join DNA fragments by forming phosphodiester bonds
- Amplify DNA fragments
Correct Answer: Join DNA fragments by forming phosphodiester bonds
Q5. Which is the most common natural vector used for bacterial cloning?
- Phage lambda genome
- Chromosomal DNA
- Plasmid
- Ribosomal RNA
Correct Answer: Plasmid
Q6. What is the purpose of a selectable marker in a cloning vector?
- To increase plasmid copy number
- To allow identification and selection of cells carrying the vector
- To encode the protein of interest
- To fluorescently label transformed cells
Correct Answer: To allow identification and selection of cells carrying the vector
Q7. Which technique uses cycles of denaturation, annealing, and extension to amplify DNA?
- Southern blotting
- Polymerase chain reaction (PCR)
- Northern blotting
- Restriction fragment length polymorphism
Correct Answer: Polymerase chain reaction (PCR)
Q8. In PCR, what is the role of Taq DNA polymerase?
- To separate DNA strands at high temperature
- To synthesize new DNA strands complementary to the template
- To add fluorescent labels for detection
- To ligate primers to DNA fragments
Correct Answer: To synthesize new DNA strands complementary to the template
Q9. Which statement correctly distinguishes transformation from transfection?
- Transformation refers to uptake of DNA by eukaryotes; transfection refers to bacteria
- Transformation is viral-mediated DNA delivery; transfection is chemical-mediated
- Transformation typically refers to bacterial uptake of DNA; transfection refers to introduction of nucleic acids into eukaryotic cells
- Transformation and transfection are identical terms
Correct Answer: Transformation typically refers to bacterial uptake of DNA; transfection refers to introduction of nucleic acids into eukaryotic cells
Q10. What is the principle behind electroporation?
- Using chemicals to make membranes permeable
- Using an electrical pulse to transiently permeabilize cell membranes for DNA entry
- Using heat shock to insert plasmids into cells
- Using viral particles to deliver DNA
Correct Answer: Using an electrical pulse to transiently permeabilize cell membranes for DNA entry
Q11. Which blotting technique is used to detect specific DNA sequences?
- Northern blot
- Western blot
- Southern blot
- Eastern blot
Correct Answer: Southern blot
Q12. Which method is used to detect specific RNA molecules?
- Southern blotting
- Northern blotting
- Western blotting
- PCR without reverse transcription
Correct Answer: Northern blotting
Q13. What is cDNA?
- Complementary DNA synthesized from mRNA using reverse transcriptase
- Chromosomal DNA free of introns
- Mutated DNA used for cloning
- DNA labeled with fluorescent dyes
Correct Answer: Complementary DNA synthesized from mRNA using reverse transcriptase
Q14. Which of the following is a common affinity tag used for recombinant protein purification?
- Promoter
- Ribosome-binding site
- His-tag (polyhistidine)
- Origin of replication
Correct Answer: His-tag (polyhistidine)
Q15. In CRISPR–Cas9 genome editing, what directs Cas9 to the target DNA?
- Primase
- Guide RNA (sgRNA)
- Reverse transcriptase
- DNA polymerase
Correct Answer: Guide RNA (sgRNA)
Q16. What short DNA motif adjacent to the target is required for Cas9 binding and cleavage?
- ORI sequence
- PAM (protospacer adjacent motif)
- TATA box
- Poly-A tail
Correct Answer: PAM (protospacer adjacent motif)
Q17. Which type of restriction enzyme typically recognizes palindromic sequences and cuts within the recognition site?
- Type I restriction enzymes
- Type II restriction enzymes
- Type III restriction enzymes
- Type IV restriction enzymes
Correct Answer: Type II restriction enzymes
Q18. Why is codon optimization performed when expressing a human gene in bacteria?
- To increase GC content only
- To change amino acid sequence for better folding
- To alter codon usage to match host tRNA abundance and improve translation efficiency
- To remove promoter elements
Correct Answer: To alter codon usage to match host tRNA abundance and improve translation efficiency
Q19. Which host system is preferred for producing recombinant proteins requiring mammalian post-translational modifications?
- Escherichia coli
- Yeast (Saccharomyces cerevisiae)
- Mammalian cell lines (e.g., CHO cells)
- Baculovirus-insect cell system
Correct Answer: Mammalian cell lines (e.g., CHO cells)
Q20. Sanger sequencing relies on which key principle?
- Real-time synthesis with fluorescent probes
- Chain termination by incorporation of dideoxynucleotides
- Mass spectrometry of nucleotides
- Sequencing by ligation using short probes
Correct Answer: Chain termination by incorporation of dideoxynucleotides
Q21. What is the main advantage of next-generation sequencing (NGS) over Sanger sequencing?
- Lower throughput
- Higher cost per base
- Parallel high-throughput sequencing of millions of fragments
- Only sequences RNA
Correct Answer: Parallel high-throughput sequencing of millions of fragments
Q22. Which viral vector is commonly favored in gene therapy for its low immunogenicity and ability to transduce non-dividing cells?
- Adeno-associated virus (AAV)
- Adenovirus
- Bacteriophage lambda
Correct Answer: Adeno-associated virus (AAV)
Q23. What is the typical biosafety level (BSL) required for routine work with non-pathogenic recombinant E. coli K-12 strains?
- BSL-1
- BSL-2
- BSL-3
- BSL-4
Correct Answer: BSL-1
Q24. In cloning, why are sticky (cohesive) ends usually preferred over blunt ends?
- Sticky ends are harder to ligate
- Sticky ends increase ligation efficiency due to complementary overhangs
- Blunt ends always create frameshifts
- Sticky ends are resistant to nucleases
Correct Answer: Sticky ends increase ligation efficiency due to complementary overhangs
Q25. What is the function of a promoter in an expression vector?
- To terminate transcription
- To initiate transcription by recruiting RNA polymerase
- To replicate the plasmid
- To tag proteins for purification
Correct Answer: To initiate transcription by recruiting RNA polymerase
Q26. Which antibiotic resistance gene is commonly used as a selectable marker in bacterial cloning vectors?
- streptavidin resistance
- ampicillin resistance (bla)
- green fluorescent protein
- kanamycin sensitivity
Correct Answer: ampicillin resistance (bla)
Q27. Which method would you use to verify the size of a cloned DNA fragment?
- Mass spectrometry
- Gel electrophoresis (agarose gel)
- ELISA
- Northern blotting
Correct Answer: Gel electrophoresis (agarose gel)
Q28. What biosafety concern is most associated with releasing genetically modified microbes into the environment?
- Enhanced nutrient cycling
- Horizontal gene transfer of engineered traits to native microbes
- Immediate extinction of wild types
- Increased oxygen production
Correct Answer: Horizontal gene transfer of engineered traits to native microbes
Q29. Which approach can reduce immune responses to viral gene therapy vectors?
- Using the highest possible viral dose
- Preexisting immunity enhancement
- Using less immunogenic vectors like AAV or employing immune suppression strategies
- Delivering vectors by contaminated needles
Correct Answer: Using less immunogenic vectors like AAV or employing immune suppression strategies
Q30. Which ethical issue is especially contentious in genetic engineering of humans?
- Editing of somatic cells for treating single-gene disorders
- Germline editing that results in heritable genetic changes
- Using bacteria to produce insulin
- Purifying recombinant proteins with affinity tags
Correct Answer: Germline editing that results in heritable genetic changes
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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