Modified Organisms are organisms whose genetic material has been intentionally altered using modern biotechnology, a process that does not occur naturally through typical reproduction or recombination. While the term applies to plants and animals, the focus often narrows to microorganisms such as bacteria and yeast, which are frequently used in controlled settings. This precise, laboratory-based modification allows scientists to introduce new functions or enhance existing characteristics.
What Defines a Modified Organism
A Modified Organism (MO), often called a Genetically Modified Organism (GMO), is defined by the stable, heritable change to its DNA achieved through genetic engineering techniques. The modification involves altering the organism’s genome by adding, removing, or changing specific sections of the genetic code. This process distinguishes it from traditional methods, such as selective breeding, which relies on natural cross-pollination or mating to gradually select for desired traits.
The alteration introduces a combination of genetic material that would not arise in nature, often involving transferring a gene from one species into another. This action bypasses natural reproductive barriers. For instance, a human gene might be placed into a bacterium, giving the microbe an entirely new function. The resulting organism carries the new genetic information in every cell and passes it down to its offspring.
Basic Techniques for Genetic Alteration
The creation of a modified organism relies on highly specific techniques developed to cut, paste, and insert DNA sequences with precision. One foundational method is Recombinant DNA technology, which involves combining DNA from two different sources to create a new molecule. This process uses specialized enzymes, known as restriction enzymes, which act as “molecular scissors” to cut DNA strands at specific recognition sequences.
The desired gene is excised and spliced into a small, circular piece of DNA called a plasmid, which acts as a vector. DNA ligase then functions as the “molecular glue” to join the gene into the plasmid. This new recombinant plasmid is introduced into the host organism, most commonly a bacterium, which replicates the foreign DNA alongside its own.
A newer and more precise method is the CRISPR/Cas9 system, which allows for the editing of genetic code with unprecedented accuracy. This system utilizes a guide RNA molecule to locate a specific target sequence in the organism’s genome. Once the target is found, the Cas9 enzyme acts as a scissor to cut both strands of the DNA. The cell’s natural repair mechanisms then fix the break, allowing scientists to insert a new gene, delete an existing one, or alter the sequence at that exact location.
Applications in Medicine and Industry
Modified organisms serve as biological “living factories” across medicine and industrial manufacturing, producing complex molecules difficult or impossible to synthesize chemically. A significant medical application is the production of human insulin by genetically modified E. coli bacteria. Scientists insert the human gene for insulin into the bacteria, which efficiently produces large quantities of the pure hormone.
These organisms are also instrumental in creating therapeutic proteins and vaccines, such as the recombinant Hepatitis B vaccine. This vaccine uses genetically modified yeast cells to produce the viral surface protein, which is purified and used to stimulate an immune response. In the industrial sector, modified microorganisms are engineered to produce enzymes used in detergents, textiles, and food processing.
Modified organisms are also being developed to produce biofuels, such as bioethanol, by engineering yeast to ferment a wider range of sugars from agricultural waste. Other applications focus on environmental cleanup, where specialized bacteria are modified to break down pollutants like crude oil or heavy metals.
Managing Modified Organisms
The use of modified organisms requires strict management protocols to ensure safety and prevent their unintended release into the environment. This control is achieved through “contained use,” which involves deploying physical, chemical, and biological barriers.
Physical barriers include specialized laboratories, fermentation tanks, and air filtration systems designed to prevent escape. Chemical barriers involve the use of disinfectants to neutralize spills or waste materials before disposal. Biological barriers are built into the organisms themselves, such as engineering them with genetic dependencies or disabling mutations that prevent their survival outside of the controlled environment.
Regulatory bodies mandate comprehensive risk assessments before any work with modified organisms can begin, classifying activities into risk levels based on the potential harm to human health and the environment. Oversight requires facilities to implement protective measures that correspond to the assessed risk, such as specialized ventilation and inactivation procedures.