Principles of Biotechnology
Biotechnology is the science of utilising biological systems or organisms to develop useful products for human welfare. The foundation of modern biotechnology rests on two key techniques: genetic engineering and bioprocess engineering. These techniques together revolutionised the scope of biotechnology by enabling targeted manipulation of genes and large-scale production of biological substances.
I. Core Techniques in Biotechnology
Genetic Engineering
- Genetic engineering is the technique of altering the chemistry of genetic material, specifically DNA and RNA. This enables scientists to introduce modified or foreign genetic sequences into host organisms, thereby changing the organism’s phenotype. The outcome of such genetic manipulation is the expression of new or improved traits in the host, which can be used for agricultural, medicinal, or industrial purposes.
Bioprocess Engineering
- Bioprocess engineering involves maintaining a contamination-free (sterile) environment during chemical and biological processes. This technique is essential for the selective propagation of only the desired microbe or eukaryotic cell. Bioprocessing ensures the efficient production of vital biological products such as antibiotics, vaccines, enzymes, hormones, and more, on a commercial scale.
II. Conceptual Background of Genetic Engineering
Comparison with Traditional Breeding
- In nature, sexual reproduction allows for the recombination of genetic traits and facilitates variation within a population. Asexual reproduction, on the other hand, retains the exact genetic composition of the parent organism. Traditional breeding methods, like hybridisation, often result in the transfer of both desired and undesired genes. This lack of precision is a limitation when trying to improve specific traits in crops or animals.
Hybridization is the process of crossing two different plants or animals to create a new one with better or desired traits. It is commonly used in farming to grow crops that are stronger, healthier, or more productive. |
- Genetic engineering resolves this problem by enabling the isolation and transfer of only the desired gene(s) into the target organism. Thus, it offers greater control, specificity, and efficiency compared to conventional breeding techniques.
III. Cloning and Replication of Foreign DNA
- A piece of foreign DNA introduced into a host organism is unlikely to replicate on its own. However, if this DNA fragment is integrated into the genome of the host, it can replicate and be inherited along with the host’s own DNA. This is made possible by the presence of a specific DNA sequence called the origin of replication (ori), which initiates the process of replication.
- To ensure successful multiplication of the inserted DNA within the host, the foreign DNA must be linked to a DNA segment containing the ori sequence. This allows the inserted DNA to replicate independently within the host cell. The process of creating identical copies of the inserted DNA segment is known as cloning.
IV. Construction of the First Recombinant DNA Molecule
- The first successful creation of a recombinant DNA molecule was achieved in 1972 by Stanley Cohen and Herbert Boyer. They worked with a plasmid—an autonomously replicating circular extra-chromosomal DNA—from Salmonella typhimurium. The objective was to insert a gene conferring antibiotic resistance into this plasmid.
- The process began with isolating the antibiotic resistance gene from the plasmid. This was accomplished using restriction enzymes, also called molecular scissors, which cut DNA at specific sequences. The isolated DNA fragment was then joined to another plasmid using the enzyme DNA ligase, which seals the two DNA segments together.
- The modified plasmid, now a recombinant DNA molecule, acted as a vector for transferring the antibiotic resistance gene into another organism. This recombinant DNA was introduced into Escherichia coli, a related bacterial species. Inside E. coli, the recombinant plasmid successfully replicated using the host’s polymerase enzymes and produced multiple copies of the inserted gene. This was the first successful demonstration of cloning a gene in a living organism.
V. Basic Steps in Genetic Modification
- There are three fundamental steps in the process of genetically modifying an organism. The first step involves the identification of DNA fragments containing desirable genes. The second step is the insertion of these DNA fragments into a suitable host organism, using a vector such as a plasmid. The final step is the maintenance and inheritance of the introduced DNA within the host, ensuring that it is passed on to future generations of the host organism.
