Is extragenomic DNA present in prokaryotes and eukaryotes? If yes, indicate their location in both the types of organisms.
Yes. extragenomic DNA is present in both prokaryotes and eukaryotes. In case ofeukaryotes, extragenomic DNA is present in two organelles, e.g., plastids and mitochondria. Extrachromosomal DNA in Prokaryotes In case of prokaryotic cells, the extragenomic DNA is present in the form of plasmids. The plasmid are circular DNA molecules, which confer
certain unique phenotypic characters to the bacteria.
One such character is antibiotic resistance to bacteria. The plasmid DNA is also used to monitor bacterial transformation with foreign DNA. Bacteria transformation is the method of
sexual reproduction in bacteria.
Extrachromosomal DNA in Eukaryotes
Mitochondrial DNA (mtDNA)is usually circular. Mitochondrial DNA spans about 16,500 DNA building blocks (base pairs) representing a small fraction of the total DNAin cells.
mtDNA contains 37 genes, all of which are essential for normal mitochondrial functions.Thirteen of these genes provides instruction for making enzymes involved in oxidative
phosporylation.
Mitochondrial genes are among the estimated 20000-25000 total genes in the human genome.
Plastids These are small bodies found free in most plant cells and are of three types leucoplast, chromoplastand chloroplast. These are double membrane bound structures for
trapping radiation and storage purpose.
It contains small, double stranded circular DNA molecules and ribosomes essential in synthesising certain proteins. As they both can synthesise proteins and replicate on their
ownthey are known as semi-autonomous organelles.
