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BioTechnology QUESTION #10577
Question 1
The 2µ plasmid used in yeast expression vectors is valued because it:
  • Integrates stably into all 16 yeast chromosomes simultaneously
  • Is a naturally occurring high-copy-number (20–100 copies/cell) plasmid in S. cerevisiae✔️
  • Confers antibiotic resistance to ampicillin in yeast cells
  • Encodes the GAL4 transcription activator for inducible expression
Correct Answer Explanation
The 2µ plasmid (so named for its 2-micron circumference) is a naturally occurring, autonomously replicating plasmid in S. cerevisiae, present at 20–100 copies per cell. Its REP genes and FLP recombinase maintain copy number. Shuttle vectors incorporating the 2µ origin of replication and yeast selectable markers (e.g. URA3, LEU2) are widely used for high-level heterologous gene expression.