Clone means 'exact copy,' so multiple organisms or organisms with the same genotype are called clones. If someone cuts ten branches from a Mango tree and plants them, they will have the same genotype, and they all are clones. The clone carries the complete characteristics of the parent plant. Usually, this cloning is done from the desired plant. If you grow a garden by cloning from that tree, you will get high-quality tea from the entire garden. At this moment, the present clonal system has been introduced in tea plantations.
Gene cloning isolates an organism's DNA, identifies the desired gene for a specific characteristic, and copies that gene. So, gene cloning is simply copying or multiplying the desired gene.
A chromosome can contain numerous genes in its DNA. Not all of these are desirable genes. Because specific genes produce specific proteins, the desired protein is first sought, and the gene that produces that protein has to be found. Typically, scientists create a gene library that catalogs an organism's DNA and searches for the desired gene from that gene library.
One of the purposes of recombinant DNA production, whether for analysis in the laboratory or the production of high-quality proteins, is to make many copies of a particular gene. Gene cloning is the creation of many exact copies of a gene.
In simple words you can define gene cloning is a method in which a gene of interest is located and copied (cloned) out of all DNA extracted from an organism. It’s a consecutive method of making identical DNA or gene used in molecular biology. DNA is a polynucleotide chain and a tiny thing that can’t be seen without a microscope. Because of being small, it is tough to copy the DNA.
The sources of genes for Gene cloning:
i. Chromosomal segments are generated without criteria to be included in the vector, and these are stored in gene libraries.
ii. Complementary DNA reverse transcribed from specific mRNA.
iii. DNA synthesized by organic chemists in a laboratory to make them work.
Different Types of Cloning:
There are different types of cloning methods.
DNA cloning is done by making recombinant DNA. It is also known as gene cloning. The desired DNA fragment from an organism is cut out and replaced in the plasmid DNA of the appropriate bacterium, resulting in the plasmid DNA becoming a recombinant DNA. Cultivation of bacteria containing this recombinant DNA in a suitable medium will produce thousands of bacteria in a short time, and each bacterium will contain the desired gene. In this way, numerous clones of the desired gene are made.
Reproductive cloning is the technique of creating a new generation with its exact mirror through the DNA of a donor cell. Dolly, the sheep, was created in this way. Cells taken from the mammary gland of a sheep are grown in culture. A sheep egg cell is then nucleated and replaced with the nucleus of a donor cell. The ovum divides with the nucleus of the donor cell to form an embryo. This embryo is placed in the uterus of a third sheep. After a certain time, the third sheep gives birth to a kid with the appearance of the donor sheep.
Steps of Gene Cloning:
Cloning a gene is a very sophisticated technique. Researchers can clone a gene from a whole animal through some basic steps. These basic steps are as follows-
1. Isolation of gene or DNA fragment: Firstly, the targeted gene should be isolated.
2. Suitable cloning vector selection: Then, you should choose the vector that can convey the gene of interest. Various vectors are available, like bacteriophages, plasmids, bacterial artificial chromosomes, etc.
3. Introducing recombinant DNA into the host cell: rDNA is introduced to the host through chemical, physical or enzymatic methods.
4. Using an antibiotic-resistant gene system, select the transformed host cell.
5. In the host cell, multiplication of the introduced gene.
6. It isolates the copies of a gene.
7. Purifying the isolated gene.
Applications of Gene Cloning:
1. Gene cloning is used in gene and DNA analysis.
2. The presence and absence of a gene can be detected via gene cloning.
3. Specific genes can be isolated.
4. The nucleotide sequence of a gene can be fixed by gene cloning.
5. Investigation of a protein/RNA function is also an application of gene cloning.
6. Mutation of a gene can also be detected by it.
7. The production of rDNA is one of the most important applications of gene cloning.
8. It is also used in pharmaceuticals.
Advantages of Gene Cloning:
Everything has its advantages and disadvantages. So cloning of a gene also has some advantages, for example-
1. Giving multiple copies of a gene or DNA is the prime advantage of gene cloning.
2. The solution to infertility.
3. It can provide organs for transplantation.
4. Offspring can be healthy.
5. The technique is less harmful.
Limitations of Gene Cloning:
Though gene cloning has many advantages, it also has some limitations. Like-
- Most techniques are time-consuming, but the gene cloning technique is not time-consuming. It takes more than three days to provide the result.
- It can be contaminated.
- Its accuracy is low.
- It losses the diversity of the gene.
- Religious problems.
After finding the polymerase chain reaction that is PCR, the gene cloning limitations were overcome in 1983. It is a cost-effective and rapid technique. It can give accurate and high performance. This can also provide more copies of genes than the conventional gene cloning technique. The main focus of the gene cloning technique is to multiply the gene or DNA. So it is the most powerful tool in molecular biology.