single cell prokaryotes, genome is organized as a single covalently closed nucleotide chain

In single cell prokaryotes, genome is organized as a single covalently closed nucleotide chain with associated proteins popularly known as a nucleoid structure. Apart from this, extrachromosomal DNA exists in the cell in form of plasmids or episomes, many of which contribute surviving property to the organism and aid in genetic material exchange. On the other hand, genomic information in eukaryotes is distributed in the form of

highly coiled chromatin materials known as chromosomes in the nucleus. Separate genome exists in the cell organelles like chloroplast and mitochondria, which are more similar to prokaryotic covalently closed circular DNA in constitution. In viruses a large variety of gcnomic constitution is observed including single or double stranded DNA or RNA as genetic material that may exist as single chain or a number of nucleic acid

chains. These genomes are generally not associated with proteins to form any nucLeoid or chromatin structure. It has been observed that with evolution complexity and redundancy in genome increases by severalfolds, although this relationship many a times is not linear.