Understanding Genetic Engineering and its Uses
Genetic Engineering: Techniques and Applications
Although the structure of DNA was discovered in the mid-twentieth century by Francis Crick and James Watson, a breakthrough occurred in the 1970s with the development of two crucial biological tools:
- Identification of restriction enzymes.
- The polymerase chain reaction (PCR).
These tools, along with a greater understanding of genes, ushered in the era of Biotechnology, a science integrating natural sciences and engineering to utilize organisms, cells, and their molecules in developing products and services. Concurrently, Genetic Engineering emerged.
Genetic engineering encompasses technologies for manipulating genes within a living being. This manipulation is ambivalent, a double-edged sword, as the same techniques can be used for healing or destruction.
Key Genetic Engineering Techniques
The primary techniques of genetic engineering include:
1. Recombinant DNA Technology
This technique allows for the isolation and manipulation of a DNA fragment from one organism and its insertion into the DNA of a host organism, creating recombinant DNA. For instance, viral DNA can be introduced into cellular DNA. Restriction enzymes, acting as “molecular scissors,” enable this by cutting DNA at specific points. This technology facilitates obtaining large quantities of DNA fragments, including desired genes. This DNA can then be incorporated into the cells of other organisms (plants, animals, or bacteria), where they can “express” the information encoded by these genes.
2. DNA Sequencing Techniques
These techniques enable the identification of the nucleotide sequence composing DNA, allowing for laboratory synthesis, gene isolation, modification, and transfer to other cells. Building upon the understanding that DNA replication involves the separation of the double helix and that DNA polymerases catalyze DNA synthesis from deoxyribonucleotides using a DNA template, DNA sequencing techniques were developed. The enzymatic sequencing method utilizes methylated DNA (one strand of the DNA helix) and a primer, which couples to the start of DNA synthesis on the template, initiating sequencing. The primer allows DNA polymerase to copy the complementary strand, directing nucleotide placement. This method has led to automated DNA sequencing, widely used today.
3. Polymerase Chain Reaction (PCR)
PCR is an in vitro (laboratory) enzymatic reaction enabling gene amplification through repeated cycles. These cycles involve DNA sequence denaturation, renaturation or hybridization (combining two single strands of complementary DNA into a double-stranded molecule) with primers, synthesis of new DNA as extensions of the primers, and denaturation again to begin the next cycle. This process increases the number of copies of a specific DNA fragment without isolating it.
Applications of Genetic Engineering
- Production of transgenic plants and animals, and animal donation.
- Procurement of Genetically Modified Microorganisms (GMMs) to produce pharmaceuticals or other useful products, such as human insulin.
- Diagnosis of inherited diseases or those caused by gene alterations. Early detection allows for appropriate treatment.
- Gene therapy to correct or replace an altered gene with a non-mutated one.
- Identification of species, determination of individual genetic fingerprints, fossil DNA sequencing, and determination of the nucleotide sequence of the genome of different species.