During the process of reproduction, essential genetic information is passed on to the new individual as part of the inheritance. Plasmid DNA is a part of extrachromosomal DNA that is separated from the genomic DNA. It typically occurs inside the prokaryotic cells and is circular in nature. When compared to chromosomes, it is a smaller molecule and may vary in its number in a particular cell. It contains an origin of replication and hence it is self-replicative inherently.
Consequently, they do not depend on genomic DNA and can self-replicate. This DNA encodes for genes whose outcomes are not essential for the functioning of the cell, such as metal resistance, nitrogen fixation, antibiotic resistance etc. Hence plasmid DNA is consumed under artificially-induced or natural conditions by both prokaryotic cells or eukaryotic cells. Therefore new genes can be inserted through the process of genetic engineering.
Chromosomal DNA, on the other hand, is the genomic DNA found in prokaryotic and eukaryotic entities. Eukaryotic genomes possess a few linear chromosomes while prokaryotic genomes carry a single circular chromosome. They are double-stranded and contain an origin of replication, the presence of more than one origin of replication in eukaryotes is credited to their large size. The chromosomal number of a particular type varies in species.
Most of the species are diploid containing two copies of a particular type of a chromosome. As it represents the genome of an individual, which is essential for the growth, evolution and reproduction of an entity, it becomes essential to be possessed by an individual as opposed to plasmid DNA.
Key differences between chromosomal DNA and plasmid DNA
| Chromosomal DNA | Plasmid DNA |
| Transfer of genetic information in the cellular form | Double-stranded DNA – Circular, small and is different from a chromosomal DNA |
| Type of genomic DNA | A form of extrachromosomal DNA |
| Larger than plasmid DNA | Smaller than chromosomal DNA |
| Found in both prokaryotic and eukaryotic cells | Found only in prokaryotes |
| Size varies. Circular in prokaryotes and linear in eukaryotes | Circular in shape |
| The number varies depending upon species | Number of occurrence in a cell varies from 1 to a thousand |
| Crucial in the development, growth and reproduction of an entity | Not essential for the functioning of the cell |
| Replicate with the genome | Can duplicate independent of the genome |
| Prokaryotes – Possess an open reading frame Eukaryotes – Possess exons and introns | Do not contain introns and exons. Possess an open reading frame |
| Transferred by cell division | Transferred by horizontal gene transfer |
| Significant in the reading of genetic information | Significant in recombinant DNA technology |
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See Also:
| DNA structure |
| Difference Between Prokaryotic And Eukaryotic DNA |
| Chromosome |
| Molecular Basis of Inheritance |
| Recombinant DNA Technology |
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