MCAT® ExamBiological and Biochemical Foundations of Living SystemsMedium
A genetic engineer is designing a vector to introduce a gene into a bacterial cell. They want to ensure that the gene is replicated independently of the bacterial chromosome and can be easily transferred between bacteria. Which of the following components would be most suitable for this purpose?
- ABacteriophage genome
- BMitochondrial DNA
- CPlasmid
- DLinear eukaryotic chromosome
Show answer & explanationAnswer & explanation
Correct answer: C. Plasmid
Plasmids are small, circular, extra-chromosomal DNA molecules found in bacteria that replicate independently and can be easily transferred between cells (conjugation), making them ideal vectors for gene transfer.
Why the other options are wrong
- A. Bacteriophage genomes integrate into the host chromosome or replicate lytically, not typically as independent, transferable units for general gene transfer.
- B. Mitochondrial DNA is found in eukaryotic cells and cannot function as an independent vector in bacteria.
- D. Linear eukaryotic chromosomes are too large, complex, and incompatible for independent replication and transfer in bacteria.
Bacterial Plasmid
Small, circular, double-stranded DNA molecule that is distinct from a bacterial cell's chromosomal DNA and can replicate independently.
- Often carry genes beneficial for survival (e.g., antibiotic resistance).
- Used extensively in genetic engineering as vectors.
- Can be transferred between bacteria via conjugation.
Memory trick: Plasmids 'P'ass genes 'P'erfectly.