Transgenic animals and protein production MCQs With Answer

Transgenic animals and protein production MCQs With Answer

Introduction: This quiz set focuses on transgenic animals and their use as bioreactors for recombinant protein production, tailored for M.Pharm students in Advanced Pharmaceutical Biotechnology. It covers theory and practical aspects: methods for generating transgenic lines, choice of promoters and signal peptides, mammary gland expression systems, genome editing strategies (CRISPR, TALEN, ZFN), cloning (SCNT), glycosylation and humanization issues, purification challenges, regulatory and ethical considerations. Questions emphasize deeper understanding of molecular tools, expression control, and downstream processing specific to pharming. Use these MCQs to test application-level knowledge needed for designing, evaluating, and troubleshooting animal-based production platforms for therapeutic proteins.

Q1. Which technique was historically the most common for creating transgenic mammals by introducing a transgene directly into a fertilized egg?

• Somatic cell nuclear transfer (SCNT)
• Pronuclear microinjection into the zygote
• Embryonic stem cell gene targeting
• Lentiviral transduction of adult tissues

Correct Answer: Pronuclear microinjection into the zygote

Q2. Which promoter is most commonly used to drive high-level, mammary gland-specific expression of recombinant proteins in milk?

• CMV immediate-early promoter
• Beta-casein promoter
• Albumin promoter
• EF1-alpha promoter

Correct Answer: Beta-casein promoter

Q3. What is a primary advantage of using goats as transgenic bioreactors for therapeutic proteins?

• They naturally produce human-like antibodies without engineering
• High milk yield and relatively short generation time
• Complete absence of glycosylation differences compared with humans
• Ease of producing proteins directly in blood serum

Correct Answer: High milk yield and relatively short generation time

Q4. To humanize glycosylation patterns in a transgenic animal you would most effectively use which strategy?

• Overexpress bacterial glycosidases in the animal
• Knockout competing endogenous glycosyltransferases and knock-in human glycosyltransferases
• Rely on natural selection to favor human-like glycosylation
• Use hydrophobic signal peptides to alter glycosylation

Correct Answer: Knockout competing endogenous glycosyltransferases and knock-in human glycosyltransferases

Q5. What is a major product-related risk when expressing human therapeutic glycoproteins in non-primate mammalian milk?

• Excessive phosphorylation of the therapeutic protein
• Differences in glycosylation leading to altered immunogenicity
• Spontaneous conversion of protein to DNA
• Guaranteed protease resistance compared to human-derived protein

Correct Answer: Differences in glycosylation leading to altered immunogenicity

Q6. Which approach is most appropriate for creating a gene-targeted large animal (cow, pig) with a precise genetic modification?

• Pronuclear microinjection of linear DNA only
• Somatic cell nuclear transfer (SCNT) using genetically modified somatic cells
• Random insertion via plasmid electroporation of embryos
• Natural breeding and selection without manipulation

Correct Answer: Somatic cell nuclear transfer (SCNT) using genetically modified somatic cells

Q7. In the context of founder transgenic animals, what does mosaicism refer to?

• The presence of multiple distinct transgenes at different loci in all cells
• Founders containing cells with different genotypes because transgene integrated after initial zygotic divisions
• Uniform expression of the transgene in all tissues
• Selective transgene loss in the germline only

Correct Answer: Founders containing cells with different genotypes because transgene integrated after initial zygotic divisions

Q8. Which genetic element is commonly included in transgene constructs to reduce position-effect variegation and transcriptional silencing?

• Origin of replication from plasmids
• Chromatin insulators such as chicken HS4
• Polyadenylation signal only
• Prokaryotic promoter sequences

Correct Answer: Chromatin insulators such as chicken HS4

Q9. Why is the mammary gland considered an attractive bioreactor for recombinant protein production?

• It secretes proteins directly into blood for easy harvest
• High-level secretion into milk facilitating easier downstream purification
• Proteins secreted into milk are always non-glycosylated and homogeneous
• Regulatory oversight is less stringent for milk-derived therapeutics

Correct Answer: High-level secretion into milk facilitating easier downstream purification

Q10. Which promoter is known for strong, often ubiquitous expression but can be susceptible to silencing in vivo?

• Beta-casein promoter
• Albumin promoter
• CMV immediate-early promoter
• Mammary-specific whey acidic protein promoter

Correct Answer: CMV immediate-early promoter

Q11. What is a typical initial step in downstream processing of recombinant proteins produced in animal milk?

• Affinity chromatography directly from whole milk without any pre-treatment
• Cream removal and casein precipitation (acid or filtration)
• Direct lyophilization of raw milk
• Incubation with proteases to reduce host proteins

Correct Answer: Cream removal and casein precipitation (acid or filtration)

Q12. Which method is best for targeted integration of a transgene into a defined “safe harbor” locus in an animal genome?

• Random pronuclear integration followed by screening
• CRISPR/Cas-mediated knock-in into a safe harbor locus (e.g., ROSA26)
• Use of BACs without genome editing
• Transfection of differentiated adult tissues with plasmids

Correct Answer: CRISPR/Cas-mediated knock-in into a safe harbor locus (e.g., ROSA26)

Q13. Which analytical method provides precise quantitation of transgene copy number in a transgenic animal?

• Western blot of tissue lysates
• Quantitative PCR (qPCR) or droplet digital PCR (ddPCR)
• Protein immunoassay of serum
• In situ hybridization only

Correct Answer: Quantitative PCR (qPCR) or droplet digital PCR (ddPCR)

Q14. Which non-human epitope is commonly introduced by some mammalian species and can trigger immune reactions in humans?

• N-linked mannose-6-phosphate epitope
• Alpha-gal (alpha-1,3-galactose) epitope
• Human poly-N-acetylglucosamine epitope
• Sialic acid identical to human Neu5Ac

Correct Answer: Alpha-gal (alpha-1,3-galactose) epitope

Q15. Which transgenic animal was used to produce the FDA-approved recombinant human antithrombin product (ATryn)?

• Transgenic cow
• Transgenic goat
• Transgenic rabbit
• Transgenic mouse

Correct Answer: Transgenic goat

Q16. Which regulatory concern is particularly relevant for production of therapeutics using transgenic animals?

• Potential horizontal transfer of the transgene to wild populations and animal welfare issues
• Guaranteed lack of post-translational modifications
• Absence of any need for clinical trials
• Unlimited scalability without impact on biodiversity

Correct Answer: Potential horizontal transfer of the transgene to wild populations and animal welfare issues

Q17. Which product quality attribute is most frequently altered when expressing human proteins in animal systems and must be characterized thoroughly?

• Primary amino acid sequence due to codon usage
• Glycosylation patterns affecting activity and half-life
• Presence of ribosomal RNA contaminants
• Intrinsic fluorescence of the protein backbone

Correct Answer: Glycosylation patterns affecting activity and half-life

Q18. For introducing a single nucleotide change into an animal genome with minimal double-strand breaks, which tool is most appropriate?

• TALEN-mediated large deletions
• CRISPR base editors
• Random chemical mutagenesis
• Conventional pronuclear injection of plasmids

Correct Answer: CRISPR base editors

Q19. Why is inclusion of a signal peptide sequence important in transgene constructs intended for secretion into milk?

• To anchor the protein permanently in the cytosol
• To direct the nascent protein into the secretory pathway for secretion into milk
• To increase nuclear localization of the protein
• To prevent any post-translational modification

Correct Answer: To direct the nascent protein into the secretory pathway for secretion into milk

Q20. Which factor most often explains large differences in expression level between independent transgenic lines carrying the same construct?

• Chromosomal integration site (position effect)
• Identical promoter strength in all lines
• Uniform copy number and expression in every case
• Presence of bacterial antibiotic resistance genes only

Correct Answer: Chromosomal integration site (position effect)

Download