Gene Cloning Definition, History, Process & Steps | What is Gene Cloning

Searching for the worth information on gene cloning on internet? Here, you will find all the basic information about gene cloning in the simplest way. Let’s start from the definition of gene cloning!

Gene Cloning Definition

The process in which the genetically identical copies of an organism are produced by natural or artificial procedures is called Gene Cloning. In the biological context, therefore a clone can be defined as a molecule, single cell or multi-cellular organism that has been directly emulated from another living organism and is therefore is identical to another living organism on the genetic basis.

Generally the term clone has been used to refer to the “natural” clones which are created when an organism shows asexual reproduction or the reproduction by chance as in case of identical twins, but mostly a clone is an identical copy which has been created intentionally with some purpose behind.

History of Gene Cloning

The viability of the cloning concept came into real picture when the scientific world witnessed one of the most significant results of the cloning experiment in which the “Dolly” was created in 1997.

Till then the cloning and its definitions were only on the papers or in the notes of scientists. We can understand cloning in number of different aspects. One such is Molecular Cloning which is actually the procedure in which DNA sequences of special interest are isolated and hence amplified in order to create number of copies of the isolated DNA.

Process of Gene Cloning

The procedure of cloning is one of the essential steps the subsequent analysis of the DNA fragments which contains genes. Molecular Cloning is sometimes referred to as Gene cloning. Cloning of any DNA sequence involves the following four steps: amplification, ligation, transfection, and screening / selection.

Amplification involves the process of making multiple copies of the gene of interest. It is carried out by PCR (Polymerase Chain Reaction) in which the ‘gene of interest is’ amplified.

The ligation step is performed in which the particular gene of interest is excised with the help of different restriction endonucleases and then ligated to a plasmid and inserted into the vector so that it can be used for the process of transfection.

In transfection, the vectors try to act competent and take up the plasmid. In order to confirm that the vector has taken up the plasmid the screening process is done. Once the screening is confirmed the amplification process is completed.

This type of cloning has paramount importance in the field of recombinant biotechnology. The other aspect in which the cloning can be understood is creating the exact copies called clones which can be done by two processes in the lab: artificial embryo twinning and somatic cell nuclear transfer.

Artificial embryo twinning can be considered as a relatively low-technology based method to make clones. As the name says, this technique tries to emulate the natural process that creates identical twins.

If we talk about nature, twins are formed at very early in developmental stages where the embryo splits in two parts. Twinning takes place while in the initial days after egg and sperm join, on the other hand the embryo is made of just a small number of unspecialized and undifferentiated cells.

Each half of the embryo will continue dividing on its own and ultimately develops into a separate and complete individual. Since the resulting individuals are developed from the same fertilized egg, they are identical on the genetic grounds.

Artificial embryo twinning takes into account the same approach as it happens in a natural process, but the difference is that it is carried out in a Petri dish instead of inside the womb of a mother.

A very early embryo is separated into individual cells, which are allowed to divide and develop for a short time in the Petri dish. These embryos are then placed into a surrogate mother, where they finish developing.

Again, since all the embryos came from the same fertilized egg, they are genetically identical. On the other hand Somatic cell nuclear transfer (SCNT) which is also called as nuclear transfer, uses altogether a different approach than artificial embryo twinning.

But both the techniques produce the same result: an exact genetic copy, or clone, of an individual. If we see the detailed meaning of the nomenclature of Somatic Cell Nuclear Transfer we get to learn the following:

Somatic cell: Any cell of the body other than sperm and egg is called a Somatic cell. Reproductive cells are also called germ cells. Generally in mammals every somatic cell has two complete sets of chromosomes that is 2n. On the other hand the germ cells have only one complete set that is half the number of chromosomes.

Image Source

Nuclear: The nucleus is the centrally located organelle that contains the DNA of a cell. The DNA is divided into packages called chromosomes which contains all the genetic information needed to form an organism and this information is passed on from generations to generations.

Each organism is unique due to the presence of that unique signature in the genetic information.

Transfer: Literal meaning of the word transfer is to move an object from one place to another. Since SCNT was involved in creating Dolly, researchers isolated a somatic cell from an adult female sheep.

Then they removed the nucleus from the cell and all of its DNA from the nucleus of an egg cell. Then they transferred the isolated nucleus from the somatic cell to the egg cell. After a number of chemical tinkering, the egg cell, with its new nucleus, was behaving just like a freshly fertilized egg.

It then went on developing into a full embryo, which was then implanted into a surrogate mother and then the surrogate mother was made to complete the full term in order to deliver the progeny.

The transfer step is one of the most important step in SCNT process and is often done using an electrical current which helps in fusing the membranes of the somatic cell and the egg cell.

The lamb Dolly which was then presented before the world was an exact genetic replica of the adult female sheep that donated the somatic cell. She was the first-ever mammal to be cloned from an adult somatic cell.

Final Words

I hope that now you have a clear idea about Cloning and different aspects associated with it. If you have any suggestion or feedback, please leave a comment below.

You can also read DNA Transcription.