Recombinant DNA: Definition, Steps, and Examples

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What is Recombinant DNA?

Recombinant DNA or rDNA refers to the molecule of DNA which are formed artificially in the laboratory, by genetic recombination.

Recombinant DNA, is a generally a piece of DNA which are formed by combining the two fragments of DNA from different sources.

This is possible because the DNA of all organisms form the same chemical formula and it differs only in formation of nucleotides.

Recombinant DNA are also called as chimeric DNA, as they are made up of two different species resembling mythical chimera. This type of technology mostly uses palindromic sequences that are used for the production of blunt and sticky ends.

Usually, DNA sequences are used for the construction of rDNA s where plant DNA can be combined with bacterial DNA or in the sense human and fungal DNA can be combined.

To be considered that these sequences are not obtained anywhere form nature and they are only synthesized chemically in a laboratory and further they are incorporated into a host cell.

And such proteins which are formed with the help of recombinant DNA technology and injected into the host cells are known as recombinant proteins.

However recombinant DNA is different from genetic recombination where rdna is formed artificially in the test tubes and later is formed by a normal biological process.

The process of producing recombinant DNA is known as recombinant DNA technology.

Recombinant DNA Process or Mechanism

Molecular cloning techniques are used to create a recombinant DNA, this method is usually known as rDNA technology and these methods are mostly performed in laboratories.

In others it is said that, the technology which helps to change the phenotype of an organism through which it is inserted. By inserting a genetically altered vector the genome of an organism may be integrated.

So generally, this process involves the introduction of foreign gene into a genome which has its gene of interest.

The gene thus introduced is known as the recombinant gene and the process is defined as recombinant DNA technology.

There are several processes, tools and enzymes which are involved in this process and they are as follows.

Recombinant DNA Technology

This technique was successful with the discovery of restriction enzymes which play an important role in forming the rDNA.

This discovery of enzymes was first proposed by Werner Arber, a swiss microbiologist in the year 1968. Inserting a target gene into a host cell is not an easy task as it sounds great.

To perform this usual selection of gene for the administration and selection of suitable vector is very much essential, where the genes have to be integrated and formation of recombinant DNA occurs.

Thus, after introducing this rDNA into the host, it is maintained and carried further to the offsprings for future generation.

Tools of Recombinant DNA

Restriction enzymes are the important tools used in the formation of rDNA. Where the polymerases help in separating the molecules and ligases help in binding to the specific site.

The restriction enzymes also play an important role in determining the location of the desired gene that where it has to be located into the vector genome.

Restriction enzymes are classified into two types as exonucleases and endonucleases.

Endonucleases helps in cutting the strand of the DNA and exonucleases are generally sequence-specific which are known as palindrome sequences which cuts the DNA at specific sites.

It also helps in sensing the length of the DNA and cut specifically at the certain site known as restriction site, which gives rise to sticky ends in the sequence.

The genes which are required are cut by the restriction enzymes to get a sticky end which are complementary for the ligases to combine through and help in binding to the vector gene.

Importance of Vectors in Recombinant DNA Technology

Vectors play a vital role in carrying and integrating a desired gene which is very important for this technology.

These vectors are generally known as vehicles that carry their desired genes into the host cell.

The most used vectors in rDNA technology are plasmids and bacteriophages.

How Recombinant DNA in Generated?

The process of formation of recombinant DNA involves the following steps.

• Isolation of genetic material: The first step involved in this process is the isolation of desired gene in its pure form which does not contain other macro or micro molecules.

• Cutting the genes at the site of recognition: The genes are cut at the determined location with the help of restriction enzyme and they are inserted into the genome of a vector. This step is generally known as “restriction enzyme digestion”.

• Amplifying of genes through PCR: In the step, a single copy of gene is amplified to produce millions of copies, when the specific gene is cut using restriction enzyme.

• Ligation: In this step the fragment of separated DNA and the vector are joined together with the help of enzyme DNA ligase.

• Insertion: Here the obtained recombinant DNA is introduced into the host cell which starts multiplying and later expresses in the form of synthesized protein and further it is transferred to the offspring.

Application of Recombinant DNA

Thus, the formed rDNA can be used in variety of fields such as research, medicine, and in biotechnology.

Now a days these proteins play a vital role in pharmaceuticals and also, the organisms which are injected with recombinant DNA has its functional role in its products and in agricultural and edible farms.

The most important use of recombinant DNA is in basic researches especially in the field of genetics and in medicine.

Recombinant DNA also helps in identifying the genomes, mapping of genomes and its specific sequences.

Probes of recombinant DNA are especially used in identifying the gene expression within a single cell and also in the tissues of a particular organism.

Whereas rDNA has also has its importance in laboratory reagents and also in generating antibodies for protein synthesis among the organisms.

Many additional applications of rDNA are found in industry, food technologies, medicine etc. such as Recombinant chymosin, recombinant human insulin, recombinant human growth hormone, recombinant blood clotting factor VIII, recombinant hepatitis -B vaccine, Golden rice, Disease resistant and herbicide resistant crops, insecticidal crops, etc.

Recombinant DNA Citations


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