Genetically Modified Organisms
Genetically Modified Organisms

A final issue that is very important to global public health is the debate over genetically modified organisms (GMO’s). Scientists, working with farmers, have now found ways to unlock the genetic codes of many plants and animals for the sake of improving these organisms. These changes may involve making them:

  • more resistant to parasites,
  • grow faster, or
  • yield higher quantities of protein.

However, this practice also has generated fierce controversy, raising concerns about the ethics of tampering with life as well as health concerns.

A GMO is an organism (either a virus, a bacterium, or a more complex life-form) whose genetic makeup has been altered by humans for a specific purpose. One of the more common motivations for genetic modification is to increase the nutritional content, yield, or pest resistance of crops.

Genetics Basics

What is a gene? Genes are the units of inheritance that are made up of DNA arranged in long strings on a cell’s chromosomes. Humans have as many as 50,000 genes (about twice as many as a flowering plant). Every cell has two copies of each gene.
What is DNA? Deoxyribonucleic acid, any of various nucleic acids that are usually the molecular basis of heredity, are located in the nuclei of cells, and are constructed of a double helix held together by hydrogen bonds. If placed end-to-end, DNA strands would stretch more than five feet but would be only 50-trillionths of an inch wide.

What is a genetic mutation? A genetic mutation is a subtle irregularity in a cell’s DNA sequence. These mutations are responsible for many inherited diseases such as cystic fibrosis and sickle cell anemia. They also may predispose an individual to cancer, major psychiatric illnesses, and other complex diseases. 

To experience the difficulty of DNA coding, visit and send each other “coded” messages.

Organisms are modified by

1) identifying the portions of deoxyribonucleic acid (DNA) that govern the trait that is to be replicated;

2) extracting the DNA from the organism;

3) introducing the DNA into a different organism; and,

4) reproducing the new organism, with the new trait.

Is this process anything new? Through selective breeding, farmers and ranchers have introduced valued traits into crops and livestock for centuries. It was selective breeding, for example, that produced two main species in the grass family, wheat and rye. Some farmers focused on breeding a grass that was rugged (resulting in rye), and other farmers focused on breeding grass with a high yield (wheat). By identifying and “crossing” grasses that exhibited the desired traits, farmers were able to breed these two distinct species.

The difference between GMOs and their selectively bred predecessors is that with selective breeding, all the traits of the desirable animal or plant are passed on to the new offspring. With genetic engineering, it is possible to isolate and introduce into another organism only those traits that one wants to pass on to that organism’s offspring.

To extend the wheat example, when farmers crossed different kinds of grass to produce grasses that grew quickly and prolifically, they had to accept that these grasses also grew very tall, and their stalks often broke before they were cultivated. With selective breeding, farmers have to accept undesirable traits along with desirable ones.

In addition, selective breeding only works with different organisms of the same or similar species, limiting the sorts of combinations that can be produced. The same limitation does not apply with GMOs. In one example, human DNA sequences were introduced into mouse DNA, creating mice that produced components for human blood that are needed in medicine. This sort of interaction is impossible with normal selective breeding.  

* Picture Source: Wikimedia


Next: Highly Beneficial: Increased Yield and Hardiness