An organic double-stranded chemical compound that encodes genetic information for the development, functioning, and reproduction of organisms and provides instructions for the synthesis of proteins is known as DNA (Deoxyribonucleic acid). All organisms contain DNA in their cells. It plays an essential role in the passing of heredity characteristics from parents to offspring.

Eukaryotic organisms are multicellular and are more complex in traits as compared to prokaryotic organisms which are unicellular in nature. Few similarities exist between prokaryotic and eukaryotic DNA like:

  • Both carry out the processes of replication, transcription, and translation
  • The ribosome is the site in both where translation occurs
  • mRNA is the primary transcript in both
  • For base-pairing DNA of both domains follow the rule of Chargaff
  • Extra-chromosomal genetic material is present in both, in prokaryotes plasmid DNA while in eukaryotes mitochondrial DNA.

Due to the complexity and similarity in their traits, both domains of organisms differ a lot on basis of the nature of DNA present in them. Following are the differences between the DNA of eukaryotic and prokaryotic organisms.

Prokaryotic DNAEukaryotic DNA
Location: DNA of prokaryotes is found inside the cytoplasm of the cell.  DNA of eukaryotes is found inside the nucleus of the cell.
Organelle of DNA: It is not present inside the organelles.  Present inside the organelles like mitochondria.
Form of DNA: Genome of prokaryotic cell is present in circular form.  Genome of eukaryotic cell is present in linear form with two ends.
Plasmid DNA: Plasmid DNA is present.    Absence of plasmid DNA.
Number of Genes: It contain few number of genes.  It contain large number of genes.
Number of Copies: It consists of one copy of genome.  It consists of more than one copy of genome.
Number of Chromosome: It is organized into a single chromosome.  It is organized into many chromosomes.
Histone Packaging: It is not packed with histones.  It is packed with histones.
Presence of Introns: No introns are present.  Introns are not absent.
Non-Functional DNA Amount of non-functional DNA is less.  Amount of non-functional DNA is high.
Site of Replication: Replication of DNA occur inside cytoplasm.  Replication of DNA occur inside nucleus.
Efficiency of Replication Process: DNA Replication process is less complex due to small size of genome and hence replication rate is rapid.  DNA replication process is more complex due larger genome size and hence replication rate is slow.
Origin of Replication: Single origin of replication.  Multiple origins of replication.
Presence of Transposons: Transposons are present.  Transposons are absent.
Size of DNA: Size of DNA is about or less than 0.1pg.  Size of DNA is more than 0.1pg
Repetitive Sequences: DNA repetitive sequences are less.  DNA repetitive sequences are common/more.
Amount of GC/AT: More GC content as compared to AT content.  More AT content as compared to GC content.
mRNA’s Nature: Poly-cistronic mRNA  Mono-cistronic mRNA

Prokaryotic DNA

DNA of prokaryotes is in circular form packed in a single chromosome and is found inside the cytoplasm. It is not enclosed in a nuclear membrane. In addition to chromosomal DNA, small, single-stranded circular plasmid DNA is also present in prokaryotes which contain additional information, and certain genes like anti-biotic resistance genes which are essential for bacterial survival. Plasmid DNA is an essential component in genetic engineering techniques.

Nucleoid is the region in the cytoplasm where the DNA resides. The chromosome is packed inside the nucleoid due to the presence of nucleoid-associated proteins. The formation of the looped configuration of DNA is due to the presence of these proteins. The major region of the prokaryotic genome is involved information of protein due to its small size. It is not folded with histone proteins because of the circular chromosomes so it does not have to fit in the nucleus.

Depending upon the type of species, the DNA of prokaryotes ranges from a few thousand to a million base pairs (about 160,000-12.2000000 bp). It is enriched with genes due to which less amount of non-functional DNA is present. Operons are the regions where functional genes are organized. Introns and exons together involve in the formation of the gene, introns are non-coding sequences and are absent in prokaryotes.

There is only one origin of replication in the chromosome of prokaryotes hence during the process of replication single replication folk and bubble will be formed. As the prokaryotic genome is less complex with less repetitive DNA sequences, therefore, the replication process is more efficient with the rapid speed of 2000 nucleotides/second.

The nature of mRNA is poly-cistronic in the transcription process. As prokaryotes are unicellular organisms hence they contain only one copy of the genome. A large number of active-transposons are present in prokaryotes, which are moveable genetic components and involve in genetic diversity.

Eukaryotic DNA

DNA of prokaryotes is in linear form present inside nucleus enclosed in nuclear membrane. Some membrane bound organelles like mitochondria and chloroplast also have some quantities of DNA inside them which is not part of genomic DNA. Bundles of chromosomes have DNA packed inside them.

Linear DNA is coiled around an alkaline protein known as histone which gives a more complex structure to DNA. Histones are the proteins that assist in the packing of chromosomes in the nucleus. Eukaryotic DNA contains telomeres at both ends which are repetitive sequences of nucleotides and provide protection to chromosomes from deterioration.

The genome of eukaryotes is made up of repetitive sequences of nucleotides. A large number of base pairs is present in the chromosomes of eukaryotes. Eukaryotes are multicellular organisms so they contain several copies of the genome. In the DNA of eukaryotes, the amount of non-functional DNA is high, due to low gene density, which plays an essential role in gene expression.

Genes are functional units of hereditary. Eukaryotic genes contain non-coding sequences known as introns. In the human genome, about 97% region consists of non-coding DNA sequences that are not involved in protein-encoding. There are multiple origins of replications and the efficiency of replication is low (100 nucleotides/second) due to the complex genome. The nature of mRNA is mono-cistronic during the process of transcription. The mobile genetic elements i.e. transposons are absent in the eukaryotic genome.

The life of an organism is not possible without DNA. DNA of prokaryotes and eukaryotes differ on basis of quantity, packing, replication, and information content. DNA of prokaryotes is organized into a single chromosome which is circular while in eukaryotes DNA is arranged in several linear chromosomes. The replication process is similar for the DNA of prokaryotes and eukaryotes but this process is simple in prokaryotes. The eukaryotic genome is larger and more complex as compared to the prokaryotic genome.

Sana Riaz
Author

Sana has just completed her MPhil in Microbiology. She loves reading books and the latest discoveries in sciences.

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