What would happen if a plasmid lacked an origin of replication?

What would happen if a plasmid lacked an origin of replication?

• A. It would still replicate using host replication
• B. It would maintain episomal as linear DNA
• C. It would integrate into the host chromosome
• D. It would not replicate and would be lost during cell divisions

Answer: (D)

Origin of replication is the site where plasmid DNA replication starts. Without this initiation point, there’s no way for the plasmid to copy itself during the cell cycle, so its copy number cannot be maintained. As cells divide, the existing plasmid copies are not replenished, and the plasmid is gradually lost from the population unless it becomes integrated or is kept by selective pressure. In bacteria, plasmids are typically circular, and linear episomal DNA or random chromosomal integration aren’t the expected outcomes from simply lacking an origin. So the plasmid would not replicate and would be lost during cell divisions.

Origin of replication is the site where plasmid DNA replication starts. Without this initiation point, there’s no way for the plasmid to copy itself during the cell cycle, so its copy number cannot be maintained. As cells divide, the existing plasmid copies are not replenished, and the plasmid is gradually lost from the population unless it becomes integrated or is kept by selective pressure. In bacteria, plasmids are typically circular, and linear episomal DNA or random chromosomal integration aren’t the expected outcomes from simply lacking an origin. So the plasmid would not replicate and would be lost during cell divisions.