plasmid – מילון אנגלי-אנגלי
Plasmid
A
plasmid is a small
DNA molecule within a cell that is physically separated from a
chromosomal DNA and can replicate independently. They are most commonly found in
bacteria as small, circular, double-stranded DNA molecules; however, plasmids are sometimes present in
archaea and
eukaryotic organisms. In nature, plasmids often carry genes that may benefit the survival of the organism, for example
antibiotic resistance. While the chromosomes are big and contain all the essential information for living, plasmids usually are very small and contain only additional information. Artificial plasmids are widely used as
vectors in
molecular cloning, serving to drive the replication of
recombinant DNA sequences within host organisms.
plasmid
Noun
1. a small cellular inclusion consisting of a ring of DNA that is not in a chromosome but is capable of autonomous replication
(hypernym) inclusion body, cellular inclusion, inclusion
Plasmid
(n.)
A piece of DNA, usually circular, functioning as part of the genetic material of a cell, not integrated with the chromosome and replicating independently of the chromosome, but transferred, like the chromosome, to subsequent generations. In bacteria, plasmids often carry the genes for antibiotic resistance; they are exploited in genetic engineering as the vehicles for introduction of extraneous DNA into cells, to alter the genetic makeup of the cell. The cells thus altered may produce desirable proteins which are extracted and used; in the case of genetically altered plant cells, the altered cells may grow into complete plants with changed properties, as for example, increased resistance to disease.
Webster's Revised Unabridged Dictionary (1913), edited by Noah Porter.
About
Plasmid
A self-replicating (autonomous) circle of DNA distinct from the chromosomal genome of bacteria. A plasmid contains genes normally not essential for cell growth or survival. Some plasmids can integrate into the host genome, be artificially constructed in the laboratory, and serve as vectors (carriers) in cloning.
plasmid
An extrachromosomal, DNA-containing entity that self-replicates within a cell.
