Genetic Engineering: History, DNA, Proteins, Techniques, The Process and Applications

It is the process of manually adding new DNA to an organism.

The goal is to provide one or more new traits that are not yet found in that orgism.

Examples of genetically modified (transgenic) organisms currently on the market include plants with resistance to some insects, plants that can tolerate herbicides and crops with modified oil content.

Historical developments

The term genetic engineering refers initially to several techniques used for the modification or manipulation of organisms through the processes of inheritance and reproduction.

As such, the term covers both artificial selection and all interventions of biomedical techniques, including artificial insemination, in vitro fertilization (for example, “test tube” babies), cloning and genetic manipulation.

In the latter part of the 20th century, however, the term came to refer more specifically to recombinant DNA technology (or gene cloning) methods, in which DNA molecules from two or more sources are combined within the cells or in vitro and then inserted into host organisms where they can spread.

The possibility of recombinant DNA technology emerged with the discovery of restriction enzymes in 1968 by the Swiss microbiologist Werner Arber.

The following year, the American microbiologist Hamilton O. Smith purified the type II restriction enzymes, which were found to be essential for genetic engineering because of their ability to cleave a specific site within DNA (as opposed to DNA restriction enzymes). type I, which cleave DNA at random sites).

Based on Smith’s work, the American molecular biologist Daniel Nathans helped advance the technique of DNA recombination in 1970-71 and demonstrated that type II enzymes could be useful in genetic studies.

Genetic engineering based on recombination was initiated in 1973 by American biochemists Stanley N. Cohen and Herbert W. Boyer, who were the first to cut the DNA into fragments, join different fragments and insert the new genes into the E. coli, which was later reproduced.

What is DNA?

DNA is the recipe of life. It is a molecule that is found in the nucleus of each cell and is composed of 4 subunits represented by the letters A, T, G and C.

The order of these subunits in the DNA chain contains an information code for the cell. Just as the English alphabet composes words using 26 letters, the genetic language uses 4 letters to spell instructions on how to make the proteins an organism will need to grow and live.

Small segments of DNA are called genes. Each gene contains instructions on how to produce a single protein. This can be compared to a recipe for making a plate of food. A recipe is a set of instructions for making a single dish.

An organism can have thousands of genes. The set of all the genes in an organism is called the genome. A genome can be compared to a cookbook of recipes that makes that organism what it is. Every cell of every living organism is like a cookbook.

Why are proteins important?

The proteins do the work in the cells. They can be part of structures (such as cell walls, organelles, etc.).

They can regulate the reactions that take place in the cell. Or they can serve as enzymes, which speeds up reactions. Everything you see in an organism is made of proteins or is the result of a protein action.

How is DNA important in genetic engineering?

DNA is a “universal language,” which means that the genetic code means the same in all organisms. It would be as if all the cookbooks around the world were written in a single language that everyone knew.

This characteristic is critical to the success of genetic engineering. When a gene for a desirable trait is taken from one organism and inserted into another organism, it gives the “receiving” organism the ability to express that same trait.

How is genetic engineering done?

Genetic engineering, also called transformation, works by physically removing a gene from one organism and inserting it into another, giving it the ability to express the trait encoded by that gene.

It’s like taking out a recipe from a cookbook and putting it in another cookbook.


Most recombinant DNA technology involves the insertion of foreign genes into the plasmids of common laboratory strains of bacteria.

Plasmids are small rings of DNA; they are not part of the bacterium’s chromosome (the main repository of the body’s genetic information).

However, they are able to direct the synthesis of proteins and, like chromosomal DNA, they reproduce and transmit to the progeny of the bacteria.

Therefore, by incorporating foreign DNA (for example, a mammalian gene) into a bacterium, researchers can obtain an almost unlimited number of copies of the inserted gene. Furthermore, if the inserted gene is operative (that is, if it directs protein synthesis), the modified bacterium will produce the protein specified by the foreign DNA.

A later generation of genetic engineering techniques that emerged at the beginning of the 21st century focused on gene editing. The genetic edition, based on a technology known as CRISPR-Cas9, allows researchers to customize the genetic sequence of a living organism by making very specific changes in its DNA.

Gene editing has a wide range of applications, which are used for genetic modification of crop and livestock plants and model laboratory organisms (eg, mice).

The correction of genetic errors associated with the disease in animals suggests that gene editing has potential applications in gene therapy for humans.

The process

1. First, an organism that naturally contains the desired trait is needed.

2. DNA is extracted from that organism. This is like taking out the entire cookbook.

3. The desired gene (recipe) must be located and copied from thousands of genes that were extracted. This is called gene cloning.

4. The gene can be modified slightly to function in a more desirable way once inside the recipient organism.

5. The new gene (s), called the transgene, are administered in the cells of the recipient organism. This is called transformation. The most common transformation technique uses a bacterium that, naturally, genetically manipulates plants with their own DNA.

The transgene is inserted into the bacteria, which then transports it to the cells of the organism being designed. Another technique, called the gene gun method, triggers microscopic gold particles coated with copies of the transgene in the cells of the recipient organism.

With any of these techniques, genetic engineers have no control over where or if the transgene is inserted into the genome. As a result, hundreds of attempts are required to achieve only a few transgenic organisms.

6. Once a transgenic organism has been created, traditional breeding is used to improve the characteristics of the final product. So, genetic engineering does not eliminate the need for traditional reproduction. It is simply a way to add new features to the group.


Genetic engineering has advanced in the understanding of many theoretical and practical aspects of genetic function and organization.

Through recombinant DNA techniques, bacteria have been created that are capable of synthesizing human insulin, human growth hormone, interferon alpha, a vaccine against hepatitis B and other medically useful substances.

Plants can be genetically adjusted to allow them to fix nitrogen and genetic diseases can possibly be corrected by replacing dysfunctional genes with genes that function normally.

However, special attention has been paid to such achievements for fear that they may lead to unfavorable and possibly dangerous traits in microorganisms that were previously free of them, for example, resistance to antibiotics, production of toxins or tendency to cause diseases.

Similarly, the application of gene editing in humans has raised ethical concerns, particularly with respect to its potential use to alter traits such as intelligence and beauty.

How does genetic engineering compare with traditional reproduction?

Although the goal of genetic engineering and traditional breeding is to improve the traits of an organism, there are some key differences between them.

While genetic engineering manually moves genes from one organism to another, traditional reproduction moves genes through mating or crossing organisms in the hope of obtaining offspring with the desired combination of traits.

Using the analogy of the recipe, traditional reproduction is like taking two cookbooks and combining all the other recipes of each in a cookbook. The product is a new cookbook with half the recipes of each original book. Therefore, half of the genes in the offspring come from each parent.

Traditional breeding is effective in improving traits, however, when compared to genetic engineering, it has disadvantages. Since breeding is based on the ability to mate with two organisms to move genes, the improvement of the trait is basically limited to traits that already exist within that species.

Genetic engineering, on the other hand, physically removes the genes of one organism and places them in the other. This eliminates the need for mating and allows the movement of genes between organisms of any species. Therefore, the potential features that can be used are virtually unlimited.

Reproduction is also less accurate than genetic engineering. In breeding, half of each parent’s genes are passed on to the offspring. This can include many undesirable genes for traits that are not desired in the new organism. Genetic engineering, however, allows the movement of one or a few genes.


In 1980 the “new” microorganisms created by recombinant DNA research were considered patentable, and in 1986 the US Department of Agriculture. UU It approved the sale of the first live genetically modified organism, a virus used as a vaccine against pseudorabies, from which a single gene was cut.

Since then, several hundred patents have been granted for bacteria and genetically altered plants.

However, patents on genetically modified and genetically modified organisms, particularly crops and other foods, were a controversial issue, and continued to be so in the first part of the 21st century.