plasmid

American  

[plaz-mid] / ˈplæz mɪd /

noun

Microbiology.

1. a segment of DNA independent of the chromosomes and capable of replication, occurring in bacteria and yeast: used in recombinant DNA procedures to transfer genetic material from one cell to another.

---

plasmid British  

/ ˈplæzmɪd /

noun

1. a small circle of bacterial DNA that is independent of the main bacterial chromosome. Plasmids often contain genes for drug resistances and can be transmitted between bacteria of the same and different species: used in genetic engineering

---

plasmid Scientific  

/ plăz′mĭd /

1. A small, circular unit of DNA that replicates within a cell independently of the chromosomal DNA and is most often found in bacteria. Certain plasmids can insert themselves into chromosomes in places where there is a common sequence of nucleotides. Plasmids contain a few genes, which usually code for proteins, especially enzymes, some of which confer resistance to antibiotics. Plasmids are used in recombinant DNA research, especially to transform bacterial cells.

2. See more at transformation

---

plasmid Cultural  

1. A circular bacterial DNA, sometimes used as a vector for gene insertion or genetic engineering. Plasmids are often the site of genes that code for resistance to antibiotics.

---

Etymology

Origin of plasmid

First recorded in 1950–55; plasm- + -id ³

Compare meaning

How does plasmid compare to similar and commonly confused words? Explore the most common comparisons:

• plasmid vs. chromosome

Example Sentences

First, the system shifted from a plasmid to the chromosome.

From Science Daily • Apr. 20, 2026

Others returned to a practice of smuggling plasmids, circular molecules of DNA used to manipulate genes, from abroad after Addgene, the U.S. nonprofit plasmid repository and distributor, stopped shipping to Russia.

From Science Magazine • Nov. 9, 2023

The ETH cell biologist and her team now plan to unravel the mysteries of the exclusome by examining cellular changes at the plasmid DNA as well as the "licence" for depositing plasmids into the exclusome.

From Science Daily • Oct. 2, 2023

In molecular cloning with bacteria, a desired DNA fragment is inserted into a bacterial plasmid using restriction enzymes and the plasmid is taken up by a bacterium, which will then express the foreign DNA.

From Textbooks • Apr. 25, 2013

To get the DNA fragment into a bacterial cell in a form that will be copied or expressed, the fragment is first inserted into a plasmid.

From Textbooks • Apr. 25, 2013