Difference Between Plasmid DNA and Chromosomal DNA

,Plasmid DNA and chromosomal DNA are two types of DNA present in bacteria. The key difference between plasmid DNA and chromosomal DNA is that plasmid DNA is not essential for the survival of bacteria while chromosomal DNA is essential for their survival since it is the genomic DNA of bacteria.

Bacteria have two types of DNA namely chromosomal DNA and extra-chromosomal DNA (plasmid DNA). Both types are circular, double-stranded DNA. Chromosomal DNA is the genomic DNA of the bacteria. It contains all genes which are necessary for the survival and contains all genetic information for their well being. Plasmid DNA contains genes which give additional advantages to bacteria such as antibiotic resistance, herbicide resistance, etc.

CONTENTS

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

What is Plasmid DNA?

Plasmid DNA is a type of extra-chromosomal DNA in bacteria. These DNA are double-stranded, circular and closed DNA loops. They are separated from genomic DNA of bacteria. They do not contain vital genes which are necessary for the survival of bacteria. But they contain genes which provide additional advantages to bacteria such as antibiotic resistance, pesticide and herbicide resistance, drought tolerance, etc. Plasmid DNA has the origin of replication. Hence, they are able to self-replicate independently of genomic DNA. They do not contain introns; neither are they coated with histone proteins.

Due to several features of plasmid DNA such as self-replication, antibiotic resistance genes, etc. they have an important role as vectors in biotechnology. Important genes can be introduced to bacteria via plasmid DNA. Therefore, plasmid DNA has a huge industrial application.

What is Chromosomal DNA?

In most living organisms, genomic DNA exists as chromosomal DNA. In bacteria, chromosomal DNA freely floats in the cytoplasm while in eukaryotic organisms, they reside inside the nucleus. Chromosomal DNA can be single-stranded or double-stranded. They can also be linear or circular. Some organisms have several chromosomes while some others, especially bacteria and archaea, have a single chromosome.

Chromosomal DNA contains all genetic information necessary for the survival and well being of the organisms. Genetic information passes from parent to offspring via the replication of chromosomal DNA. It duplicates during cell division. Furthermore chromosomal DNA contain introns as well as exons. These DNA are also tightly packed with histone proteins.

What are the Similarities Between Plasmid DNA and Chromosomal DNA?

• Both plasmid DNA and chromosomal DNA are in bacteria.
• They contain genes and are composed of DNA.
• They are important.

What is the Difference Between Plasmid DNA and Chromosomal DNA?

Plasmid DNA is the extra-chromosomal DNA of bacteria while chromosomal DNA is the genomic DNA of living organisms. Plasmid DNA is not important for the survival of bacteria while chromosomal DNA is extremely important for their survival. This is the key difference between plasmid DNA and chromosomal DNA. Moreover, plasmid DNA is smaller in size than chromosomal DNA.  The former provides extra characteristics to bacteria for survival under harsh environmental conditions while the latter provides all information for the regular well-being of bacteria

Furthermore, bacteria have a variable number of plasmid DNA while there is only one chromosome in bacteria. Plasmid DNA is always circular while chromosomal DNA can be either linear or circular. Moreover, plasmid DNA is always double stranded while chromosomal DNA can be single-stranded or double-stranded. The former is not packaged with histone proteins while the latter is packaged with histone proteins. Plasmid DNA do not contain introns or vital genes. But, chromosomal DNA contains both introns and exons as well as all vital genes.

Summary – Plasmid DNA vs Chromosomal DNA

To sum up, plasmid DNA and chromosomal DNA are two important types of DNA. Plasmid DNA provides additional characteristics to bacteria which are important to survive under harsh conditions. Moreover, they are used as vectors in genetic engineering. In contrast, chromosomal DNA is the genomic DNA that contains genetic information of an organism. Genomic DNA is important for the survival of the organism. This is the difference between plasmid DNA and chromosomal DNA.

Reference:

1.“ Plasmid.” Wikipedia, Wikimedia Foundation, 25 May 2018, Available here
2. “What Is a Chromosome? – Genetics Home Reference.” U.S. National Library of Medicine, National Institutes of Health, Available here.

Image Courtesy:

1. “Plasmid (english)” By User:Spaully on English wikipedia – Own work (CC BY-SA 2.5) via Commons Wikimedia
2. “156404” (CC0) via Pixabay