An Overview
Bacteria are the most abundant living organisms on the Earth and one of the earliest life to evolve, i.e. it was over two to three billion years before eukaryotes appeared.
A bacterial plasmid is an extrachromosomal circular DNA found naturally in bacteria, archaea, and eukaryotes.
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Structure and Functions of Bacterial Plasmid
These plasmids are small, circular, double-stranded DNA structures naturally found in all bacterial cells. These plasmids are much smaller than the primary chromosomal DNA. The size of plasmids vary from 1 to 1000 kbp, and they usually contain 5 to 100 genes.
All bacteria have plasmids that occur naturally, and they play an essential role as vectors and help in the survival of the bacteria under stressful conditions. Every bacterial cell has its plasmids involved in food digestion, facilitating replication, etc.
pBR322, pUC18, Ti plasmid are a few examples of bacterial plasmids.
Explore more:Do All Bacteria Have Plasmids?
Components of a Bacterial Plasmid
The bacterial plasmid contains DNA as genetic material, replicating independently and comprising antibiotic-resistant genes.
Many antibiotic-resistant genes in bacteria are present in plasmids.
The three necessary functional regions present within the plasmid are:
- An origin of replication
It is a sequence of DNA that initiates replication on a plasmid.
- An antibiotic resistance gene.
There are several antibiotic resistance genes present on the same plasmid.
Resistance A, B, and C are a few examples of the antibiotic resistance gene. These genes are transferred from cell to cell by conjugation, transformation, or transduction.
Explore more:Bacterial Genetics
- A polylinker to clone the gene of interest.
This is also called a multiple cloning site where the restriction enzymes cleave.
- A promoter region that causes transcription of the target gene.
It is an essential component required for expression vectors. These vectors help determine which cell types the gene is expressed in and the amount of recombinant protein obtained. Some plasmids also have selectable markers for use in other cell types.
Explore more:What Are Selectable Markers?
Stay tuned to BYJU’S Biology to know more about the plasmids, bacterial plasmids, structure, functions, and characteristics.
Frequently Asked Questions on Bacterial Plasmid Contain
What are the applications of plasmids?
Plasmids are used to prepare recombinant DNA with the desired gene to transfer genes from one organism to another. This is known as genetic engineering.
Are plasmids found in all bacteria?
Yes. Plasmids naturally exist in all bacterial cells.
These plasmids are found within the bacterial cell’s cytoplasm, and they are usually found separated from the chromosomes.
What is the role of plasmids in bacteria?
In bacterial cells, the plasmids play a vital role in:
- Help in the conjugation of bacteria.
- Enable the metabolism of nutrients.
- Transfer the information from one cell to another.
- Plasmids are also used as cloning vectors in various recombination experiments.
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