Index
It is the process of manually adding new DNA to an organism.
The goal is to provide one or more new traits not yet found in that orgasm.
Examples of genetically modified (transgenic) organisms currently on the market include:
- Plants are resistant to some insects.
- Plants that can tolerate herbicides.
- Crops with modified oil content.
Historical developments
Genetic engineering refers to several techniques used to modify or manipulate organisms through the processes of inheritance and reproduction.
The term covers the 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 essential for genetic engineering because they could cleave a specific site within DNA (as opposed to DNA restriction enzymes). Type I, which cleaves DNA at random places).
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 helpful 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 pieces and insert the new genes into the E. coli, which was later reproduced.
What is DNA?
DNA is the recipe for life. It is a molecule 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 four letters to spell instructions on making 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 essential?
The proteins do the work in the cells. They can be part of structures (cell walls, organelles, etc.).
They can regulate the reactions that take place in the cell. Or they can serve as enzymes, which speed up reactions. Everything you see in an organism is made of proteins or results from a protein action.
How is DNA essential 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 worldwide 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, it gives the “receiving” organism the ability to express that 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, allowing it to express the trait encoded by that gene.
It’s like taking out a recipe from a cookbook and putting it in another cookbook.
Techniques
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 central repository of the body’s genetic information).
However, they can direct the synthesis of proteins, and, like chromosomal DNA, they reproduce and transmit to the progeny of the bacteria.
Therefore, researchers can obtain an almost unlimited number of copies of the inserted gene by incorporating foreign DNA (for example, a mammalian gene) into a bacterium. Furthermore, if the inserted gene is operative (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 specific changes in its DNA.
Gene editing has a wide range of applications used for genetic modification of crop and livestock plants and model laboratory organisms (e.g., 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 extracted genes. This is called gene cloning.
4. The gene can be modified slightly to function more desirably 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 genetically manipulates plants with their DNA.
The transgene is inserted into the bacteria and transported to the organism’s designed cells. Another technique, called the gene gun method, triggers microscopic gold particles coated with copies of the transgene in the cells of the recipient organism.
Genetic engineers have no control over where or if the transgene is inserted into the genome with these techniques. 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 conventional reproduction. It is simply a way to add new features to the group.
Applications
Genetic engineering has advanced the understanding of many theoretical and practical aspects of gene function and organization.
Through recombinant DNA techniques, bacteria have been created capable of synthesizing human insulin, human growth hormone, interferon-alpha, a vaccine against hepatitis B, and other medically beneficial substances.
Plants can be genetically adjusted to fix nitrogen, and genetic diseases can be corrected by replacing dysfunctional genes with normally functioning genes.
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, human gene editing has raised ethical concerns, particularly concerning its potential 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 critical 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 recipe analogy, traditional reproduction is like taking two cookbooks and combining all the other recipes 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 effectively improves traits; however, it has disadvantages compared to genetic engineering. Since breeding is based on the ability to mate with two organisms to move genes, the improvement of the trait is limited to features that already exist within that species.
On the other hand, genetic engineering 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. Half of each parent’s genes are passed on to the offspring in inbreeding. This can include many undesirable genes for traits not desired in the new organism. Genetic engineering, however, allows the movement of one or a few genes.
Controversy
In 1980 the “new” microorganisms created by recombinant DNA research were considered patentable, and in 1986, the US Department of Agriculture. UU 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, mainly crops and other foods, were controversial and continued to be so in the first part of the 21st century.
