Difference Between Genomic and Plasmid DNA

The key difference between genomic and plasmid DNA is that genomic DNA is essential for the survival of organisms including bacteria while plasmid DNA is not essential for the survival of bacteria.

Every living organism has genetic material that controls its overall functioning. Genetic material mainly exists as chromosomal DNA. In eukaryotes, genomic DNA is present inside the nucleus while in prokaryotes, genomic DNA is present in the cytoplasm. Other than chromosomal DNA or genomic DNA, some organisms, including bacteria, archaea, and yeast, have extra-chromosomal DNA known as plasmid DNA. Plasmid DNA is not essential for the day to day functioning of these organisms. However, they provide some additional advantages to these organisms since it contains several important genes. It is also important to note that these genes are not as vital as the genes present in genomic DNA. So, this article attempts to discuss the difference between genomic and plasmid DNA.

CONTENTS

1. Overview and Key Difference
2. What is Genomic DNA
3. What is Plasmid DNA
4. Similarities Between Genomic and Plasmid DNA
5. Side by Side Comparison – Genomic vs Plasmid DNA in Tabular Form
6. Summary

What is Genomic DNA?

Genomic DNA represents the genetic material of an organism. In most living organisms, genomic DNA exists as chromosomal DNA. Prokaryotes have genomic DNA in their cytoplasm while eukaryotes have genomic DNA in their nucleus. Chromosomal or genomic DNA can be single-stranded or double-stranded and linear or circular. Eukaryotes possess several chromosomes while prokaryotes, especially bacteria and archaea, have a single chromosome. Genomic DNA contains the overall genetic information that is vital for the survival and well being of the organisms. Moreover, genomic DNA is the heredity material of an organism. Offspring receives genetic material from their parents. Thus, the genetic information passes from generation to generation via the replication of chromosomal DNA. It duplicates during cell division. Furthermore, chromosomal DNA contains coding as well as non-coding sequences and these DNA are tightly packed with histone proteins in eukaryotes.

Genomic DNA encodes proteins, which are responsible for structural and functional proteins. Moreover, Genomic DNA is visible only in the prophase of cell division as chromosomes; otherwise, it appears as a bundle of strings called chromatin.

When the complexity of the organism is higher, more DNA can be found in the genome. In a human, there are three billion base pairs and 23 pairs of chromosomes. On the other hand, small bacteria especially Escherichia coli have 4.3 million base pairs.

What is Plasmid DNA?

Plasmid DNA is a type of extra-chromosomal DNA present in bacteria, archaea, and yeast. It is double-stranded, circular and closed loops. Prokaryotic cells have plasmids in addition to their genomic DNA. Plasmid DNA elements also have few genes. But these genes are not essential for the function of bacteria. However, these genes provide extra survival to the cell. One bacteria cell has several copies of plasmids.

Bacteria occur in extreme conditions too, so they need defense mechanisms. The genes present in plasmids are responsible for antibiotic resistance and metabolism of some substrates such as β-galactosidase.

Plasmids help in the exchange of genes horizontally between bacteria. But, this is not a step of cell division. Some plasmids can be exchanged between two different species. It helps to spread important trait for survival such as antibiotic resistant gene throughout the bacterial population.

What are the Similarities Between Genomic and Plasmid DNA?

• Genomic and plasmid DNA are two types of DNA present in living organisms.
• They contain genes.
• Both types of DNA are present in bacteria and archaea.
• Also, the building blocks of both are deoxyribonucleotides.
• Moreover, both are double-stranded.

What is the Difference Between Genomic and Plasmid DNA?

Genomic DNA and plasmid DNA are two types of DNA in living organisms. Genomic DNA is the chromosomal DNA of living organisms that contain genetic information. On the other hand, plasmid DNA is extrachromosomal DNA present in bacteria, archaea, and some eukaryotes. Thus, the key difference between genomic and plasmid DNA is that the genomic DNA is essential for the survival of organisms while plasmid DNA is not essential for the survival of organisms. Also, a further difference between genomic and plasmid DNA is their sizes. Genomic DNA is many times larger than the plasmid DNA.

Moreover, genomic DNA contains vital genes that produce all structural and functional proteins. But, plasmid DNA contains genes that provide additional advantages for the organisms. Hence, this is also a difference between genomic and plasmid DNA.

Below info-graphic presents more information on the difference between genomic and plasmid DNA, comparatively.

Summary – Genomic vs Plasmid DNA

Bacteria comprise two types of DNA as chromosomal DNA and extra-chromosomal DNA known as plasmid DNA. Both types are circular double-stranded DNA. In summarizing the difference between genomic and plasmid DNA, the chromosomal DNA is considered as genomic DNA of bacteria. It contains all genes which are necessary for the survival of them and contains all the genetic information for their well being. Whereas, plasmid DNA contains genes which give additional advantages to bacteria such as antibiotic resistance, herbicide resistance, etc. Thus, genomic DNA is important for the heredity of organisms while plasmid DNA is important for providing extra benefits for survival.

Reference:

1. “Plasmid/plasmids” Nature News, Nature Publishing Group, Available here.
2. “Genomic DNA.” Genomic DNA – an Overview | ScienceDirect Topics, Available here.

Image Courtesy:

1. “Chromosome-DNA-gene” By Thomas Splettstoesser (www.scistyle.com) – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Plasmid (English)” By User:Spaully on English wikipedia – Own work (CC BY-SA 2.5) via Commons Wikimedia