What defines a plasmid in prokaryotic cells?

A plasmid in prokaryotic cells is defined as a small, circular piece of DNA. Plasmids are distinct from the primary bacterial chromosome; they are separate, extrachromosomal DNA molecules that typically carry a small number of genes, which can provide advantageous traits such as antibiotic resistance or metabolic capabilities. Their circular structure allows them to replicate independently of the chromosomal DNA within the cell. Plasmids can be transferred between bacteria through processes like conjugation, which contributes to genetic diversity and adaptability in prokaryotic populations. This unique feature, along with their specific size and shape, clearly distinguishes plasmids from other DNA structures or molecules in prokaryotic cells.