Cloning Vector concepts genetic engineering

Description

Plasmids are extrachromosomal, double standard, circular, self-replicating DNA molecules. Almost all the bacteria have plasmids containing a low copy number (1-4 per cell) or a high copy number (10-100 per cell). The size of plasmids varies from 1 to 500 kb. Usually, plasmids contribute to about 0.5 to 5.0% of the total DNA of bacteria.
Example:

Streptomyces sp.

A plasmid is a naturally occurring extrachromosomal double stranded DNA, circular DNA.

It replicates autonomously within bacterial cell.

Plasmid carries an origin of replication.

Plasmid vectors are the simplest cloning vectors.

It is most widely used for gene cloning.

Characteristics of Plasmid vector:

It contains an origin of replication.

It also Contain selective marker such as antibiotic resistance, blue white screening).

Small in size (1.0 to 250kb)

Contains multiple cloning site.

Easily isolated from the host cell.

Examples of plasmid vectors are:

pBR322

pUC 18/19

pBR322 vector

It is one of the first vectors to be developed by Boliver and Rodriguez in 1977.

in this concept following details will be covered.

Types of cloning vectors, plasmids,  Bacteriophages, cosmids, phasmids, lamda

Different types of plasmids

Fertility plasmids

Resistance plasmids

Col plasmids

Degradative plasmids

Virulence plasmids

Conjugative plasmids

Non Conjugative plasmids

Stringent plasmids

Relaxed plasmids

pbr322

puc19

Plasmid applications

applications of Bacteriophages

types of vectors:

PLASMIDS

BACTERIOPHAGES

COSMIDS

Degradative Plasmids

Degradative plasmids help the host bacterium to digest compounds that are not commonly found in nature, such as camphor, xylene, toluene, and salicylic acid. These plasmids contain genes for special enzymes that break down specific compounds. Degradative plasmids are conjugative.

Virulence Plasmids

When a virulence plasmid is inside a bacterium, it turns that bacterium into a pathogen, which is an agent of disease. Bacteria that cause disease can be easily spread and replicated among affected individuals. The bacterium Escherichia coli (E. coli) has several virulence plasmids. E. coli is found naturally in the human gut and in other animals, but certain strains of E. coli can cause severe diarrhea and vomiting. Salmonella enterica is another bacterium that contains virulence plasmids.

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