In this explainer, we will learn how to describe some applications of genetic engineering and discuss the advantages and disadvantages of these applications.
While genetic engineering may sound like a futuristic topic, the fact is that we have been practicing a form of it for millennia. Do you recognize this ancestor of a delicious fruit in the picture below?
It is a wild banana! It looks different from a modern-day banana because of its small size and large seeds. Over thousands of years, desirable versions of the banana plant have been selectively bred by farmers to create the modern banana we are more accustomed to eating.
Thousands of years is way too long a time to wait for a snack though! Genetic engineering is the time-saving solution to this problem. Genetic engineering refers to the process of modifying an organism’s genome artificially. Through genetic engineering, we are able to choose desirable genes from any organism and introduce them into the genome of plants or animals to obtain organisms with desired traits in much shorter period of time.
Key Term: Genetic Engineering
Genetic engineering is the artificial manipulation of an organism’s genome using biotechnology tools.
Definition: Genome
The genome is all the genetic material of an organism.
Example 1: Understanding the Concept of Genetic Engineering
Which of the following would be an example of an organism modified by genetic engineering?
- Cows that produce large amounts of milk and have high fertility were selected to breed over cows that do not to create modern dairy cows.
- Golden rice is produced by inserting the gene for vitamin A production into the genome of common rice strains.
- Pugs with a small body and flat face were bred together to make characteristics that were more desired by humans.
- Legumes, like peas and beans, have nitrogen-fixing bacteria on their roots, which helps increase soil nitrogen.
Answer
Genetic engineering is the artificial manipulation of an organism’s genome using biotechnology tools. This technology can be very useful in producing plants or other organisms with specific traits that can help humankind (for example, engineering plants to have resistance to pests to limit the use of insecticides). With genetic engineering, the genome of an organism is manipulated. The genome is the total DNA of an organism. So, in this question, we are looking for the answer that describes the manipulation of a genome.
In A, the cows were selected to breed. No artificial manipulation of their genome using biotechnology was performed, so this is an example of selective breeding and not genetic engineering.
In B, the rice is modified by inserting the gene for vitamin A into the genome of the rice plant. “Inserting” a gene implies that the gene for vitamin A was introduced into the genome artificially using biotechnology. So, this is an example of genetic engineering.
In C, the pugs were bred to give desirable traits. This is an example of selective breeding, and no artificial manipulation of the genome took place. So, this is not an example of genetic engineering.
In D, the property of the legumes is a desirable trait for genetic engineering and is something farmers would probably find beneficial for their crops, but this is only describing a general property of the legume and does not explicitly say anything about modifying the genome of the plant. So, this is not an example of genetic engineering.
Therefore, the correct answer is B: golden rice is produced by inserting the gene for vitamin A production into the genome of common rice strains.
You may recall that recombinant DNA is the creation of new genetic information from multiple sources of DNA. Genetic engineering usually involves the production of recombinant DNA because we want to introduce desirable traits from one genome into another. For example, by taking the gene of human insulin and inserting it into bacterial DNA, we can create recombinant DNA as shown in Figure 2 below. However, not all cases of genetic engineering involve creating recombinant DNA. In some cases, we may simply want to edit an existing gene or swap one out for another version of the same gene from the organism’s genome.
Key Term: Recombinant DNA
Recombinant DNA is the combination of DNA from at least two sources to form new genetic information not previously found in the genome.
Example 2: Understanding the Uses of Recombinant DNA
Which of the following is not a use of recombinant DNA?
- Producing insulin to treat diabetics using bacterial cells
- Treating a patient suffering the genetic disorder thalassemia with bone marrow cells from a healthy donor
- Modifying bacterial genomes to produce antigens of pathogens, creating safe vaccines
- Modifying plant genomes to produce crops that are resistant to certain diseases
Answer
Recombinant DNA is the combination of DNA from at least two different sources to create new genetic information not previously found in the genome. So, there are really two key parts to this definition:
- The DNA needs to be combined from at least two sources.
- This combination needs to make new genetic information not found in the genome.
Let’s look at the possible answers and see which answer best fits the definition of recombinant DNA.
In A, producing insulin to treat diabetics using bacterial cells is an example of recombinant DNA. In order to do this, the gene for human insulin needs to be combined with the plasmid DNA of a bacterium. This is combining DNA from two sources and introducing human insulin into the bacterium, which is new to the bacterial genome.
In (B), Treating a patient suffering the genetic disorder thalassemia with bone marrow cells from a healthy donor is not an application of recombinant DNA technique. This is an example of cell transplantation in which healthy cells are implanted into a patient to have a therapeutic effect. The DNA contained in the bone marrow cells doesn’t recombine with the DNA of the patient. Therefore, this answer choice does not describe the combination of DNA from two sources and does not describe the introduction of new genetic information into the genome.
In C, modification of bacterial genomes to make antigens against pathogens for vaccines is an example of recombinant DNA. There are two sources of DNA (bacterial DNA from the bacterial genome) and the antigen DNA from the pathogen. The antigen DNA from the pathogen is novel in the bacterial genome.
In D, modifying plant genomes to produce crops that are resistant to certain diseases would be an example of recombinant DNA. For example, a fungus called TR1 threatened to wipe out banana crops in the 1960s, forcing cultivators to switch to another variety of banana that was resistant to TR1. These days, it would have been possible to engineer the original banana variety to include resistance to TR1. In this example, two sources of DNA are being combined (banana DNA from the nonresistant banana and banana DNA from the resistant banana), and new genetic information is being created (the nonresistant variety now has resistance to TR1 that did not exist before).
Therefore, the correct answer is B: Treating a patient suffering the genetic disorder thalassemia with bone marrow cells from a healthy donor.
There are many applications of genetic engineering. In this explainer, we will first discuss the medical applications, like producing insulin for humans. Then, we will look at how genetically modified organisms (GMOs) like plants and animals are useful for society.
Definition: Genetically Modified Organism (GMO)
A GMO is an organism whose DNA has been altered by genetic engineering.
Insulin is a hormone that is involved in glucose regulation, and without adequate production in the body, it can lead to the disease diabetes. Genetic engineering of bacteria to produce insulin has changed the way we manufacture insulin. By combining the gene for human insulin with bacterial plasmid DNA, as shown in Figure 3, the resulting recombinant DNA can be introduced into bacteria and insulin can be abundantly manufactured for medical purposes.
Another good example of a medical application for genetic engineering is with interferons, which are proteins that are useful in combating viral infection.
Before genetic engineering was widely available in the 1970s, interferons were extracted from human cells and this process was very expensive. However, In the 1980s, researchers introduced interferon genes into bacteria to produce recombinant DNA so that they could be manufactured by the bacteria. This application of genetic engineering has significantly lowered the cost of this medical treatment.
While there are obvious medical advantages in using genetic engineering, there are also some disadvantages. One disadvantage is that the bacteria that are used in generating the recombinant DNA contain antibiotic resistance markers within their plasmids. It is possible that these plasmids can be spread to other disease-causing bacteria to create antibiotic resistance. This is possible because of a process called conjugation in which two bacteria can come in close contact and transfer genetic material by forming a bridge-like structure. You can see this in Figure 4 below.
While using bacteria as protein production factories has very practical medical applications, genetic engineering is also useful in agricultural practices.
Genetically modified crops are grown all across the world and were first introduced in 1994. In 2015, these crops were grown in 28 countries. The USA, Brazil, and Argentina are the leading producers, with more than half of their farmable land dedicated to growing these crops. People are often worried about the safety of genetically modified crops. However, according to the World Health Organization, all genetically modified foods currently available have passed safety assessments and no effects on human health have been shown.
Plants can be engineered to carry pest resistance. Many crops die each year from insects and insecticides, which can be very costly and damaging to the environment. A toxin from the bacterium Bacillus thuringiensis (Bt) is an effective insecticide, and when it is genetically engineered into plants, it can pass this trait to the plant itself. Insects that eat the plant material also consume the Bt toxin that forms pores in the cells of the insect gut and leads to death. One of the reasons the Bt toxin is considered safe for consumption is because it is only activated in the basic pH environment of the insect gut. Mammalian stomachs, like human stomachs, are acidic and, therefore, are unaffected by the Bt toxin, as shown in Figure 5.
By using the Bt toxin, less insecticides need to be used, which reduces costs for the farmer and, therefore, the overall cost of the food. Since less pesticides need to be used in Bt-toxin-engineered crops, this also helps protect the environment.
Another great example of plant genetic modification is with golden rice. In developing countries, vitamin A deficiency is a major problem that can cause acquired blindness if left untreated. Moreover, it has been reported that every year, over a million children die as a result of vitamin A deficiencies. Golden rice is rice that has been genetically engineered to contain high levels of beta-carotene, a precursor to vitamin A, giving the rice a golden color, as shown in the picture below. In this way, genetic engineering of rice has made it more nutritious, and encouraging people to consume golden rice has decreased vitamin A deficiencies.
Example 3: Understanding the Utility of Genetic Engineering in Plants
Which of the following would not be an example of an organism modified by genetic engineering?
- Soybeans have been made to express an enzyme that helps them develop a tolerance to herbicides.
- A species of corn has had the gene for an insect toxin inserted into its DNA, meaning it has developed some pest resistance.
- Seedless grapes are sprayed with solutions containing the hormone gibberellin to increase their size.
- A species of tomato has the gene for a specialized salt pump inserted into its DNA, meaning it can grow in very salty soil.
Answer
Genetic engineering is the artificial manipulation of an organism’s genome using biotechnology tools. This technology can be very useful in producing plants or other organisms with specific traits that can help humankind (for example, engineering plants to have resistance to pests to limit the use of insecticides). With genetic engineering, the genome of an organism is manipulated. The genome is the total DNA of an organism. So, in this question, we are looking for the answer where the genome is not modified.
In A, the soybeans have been made to express an enzyme, meaning the soybeans have been modified to carry the gene for that enzyme that can be expressed to make the protein. This is genetic engineering; therefore, A is not the correct answer.
In B, corn has a gene for an insect toxin inserted into its DNA, which modifies the genome of corn and is, therefore, genetic engineering.
In C, grapes are sprayed with a hormone to increase their size. Since there is no manipulation of the genome, this is not genetic engineering, so C might be a good choice as the answer. However, let’s examine the remaining choice to ensure we have the best possible answer to the question.
In D, the gene for a salt pump is inserted into the DNA of a tomato plant, which is modification of the tomato plant DNA and is genetic engineering.
Therefore, the correct answer is C: seedless grapes are sprayed with solutions containing the hormone gibberellin to increase their size.
The technology of genetic engineering has some disadvantages. Some people fear that these desirable traits can be passed onto other plants, potentially creating superweeds that would be difficult to eliminate. There is also reduced genetic diversity since many of the same kinds of crops are being grown across the world. This could lead to problems if faced with a single disease that could wipe out all the crops. By introducing new genes not previously encountered before, there is also the possibility of some individuals developing allergic reactions. Despite this, there is no evidence of negative effects on human health. Still, there are groups and countries that oppose the use of genetically modified foods because of these disadvantages, and there is uncertainty of long-term outcomes.
Example 4: Describing the Disadvantages of Genetic Engineering in Plants
Which of the following is a disadvantage of creating genetically modified crops?
- Genetically modified crops have been widely discredited as viable sources of food for humans and can only be fed to livestock.
- Genetically modified crops generally contain lower amounts of vitamins and minerals than naturally grown crops.
- Genetically modified crops have to be treated with larger volumes of pesticides than organic crops.
- Genetically modified crops face resistance from some farmers, campaign groups, and countries that do not want them grown.
Answer
Genetic engineering is the artificial manipulation of an organism’s genome. The genome is the total DNA inside an organism. Plants, among other organisms, can be genetically modified to carry traits that offer certain advantages, like resistance to disease, pests, or drought, and, in some cases, plants can be modified to be more nutritious. Many countries around the world use these modified plants, but there is still uncertainty among certain farmers and other groups of people.
Let’s look at the different answers to see which one is a disadvantage of creating genetically modified crops.
In A, the statement “genetically modified crops have been widely discredited as viable sources of food for humans and can only be fed to livestock” is not accurate. Many countries across the world grow genetically modified crops for human consumption. According to the World Health Organization, all genetically modified foods currently available have passed safety assessments and no effects on human health have been shown.
In B, the statement “genetically modified crops generally contain lower amounts of vitamins and minerals than naturally grown crops” is not accurate and, in some instances, genetically modified crops can be made more nutritious, which is a clear advantage.
In C, the statement “genetically modified crops have to be treated with larger volumes of pesticides than organic crops” is not accurate since genetically modified crops can be engineered to have pest resistance, which would require less pesticides (and this is an advantage).
In D, the statement “genetically modified crops face resistance from some farmers, campaign groups, and countries that do not want them grown” is accurate and is a disadvantage since there is uncertainty about their long-term use, which is causing resistance from certain groups of people.
Therefore, the correct answer is D: genetically modified crops face resistance from some farmers, campaign groups, and countries that do not want them grown.
So, what about animals? Are there genetically modified animals in use today? Yes, there are. And like genetically modified plants, there are extremely practical examples out there. For example, AquAdvantage salmon are salmon that have a modified growth hormone gene to allow them to grow beyond their seasonal limits for the entire year and to grow faster. Larger and faster-growing salmon increase the food supply available to humans.
Another example of genetically modified animals are mice used in research settings. These mice can be engineered to carry human genes, or the mouse genes can be modified or even deleted. These genetically modified mice can be useful as disease models to mimic the biology of specific diseases. This makes it possible to study diseases like cancer in living organisms inside a lab environment.
Some examples are less practical and more about aesthetics.
GloFish are a type of fish that are engineered to emit bright fluorescent colors and can even glow in the dark! The glow in GloFish comes from GFP (green fluorescent protein), a fluorescent protein discovered in jellyfish that has many uses in biotechnology. Variations of the GFP gene can be made to give different colors like “electric green,” “moonrise pink,” and “sunburst orange,” as you can see below.
While there are many applications for genetic engineering in plants and animals, the situation is a bit different for humans due to ethical concerns.
When it comes to modifying human DNA, much more consideration is needed to understand the ethics of genetic engineering. This is a matter of the implications of the technology and whether using it would be morally right or wrong.
Key Term: Ethical Concerns in Biotechnology
Ethical concerns in biotechnology relate to the moral principles of the technology and whether using it would be right or wrong.
Should we be able to modify human DNA? The medical benefits can be very impressive by opening the door to new treatments for diseases like heart disease, Alzheimer’s disease, and cancer. But with these applications comes morally gray areas, like modifying human DNA for aesthetics like eye or hair color, or giving measurable advantages, like increased strength or even intelligence. Moreover, the rights and personhood of such individuals is unknown and unclear. Therefore, given the unclear ethical and moral consequences, the scientific community has abstained from performing genetic engineering experiments on human tissues, like embryos.
In violation of the stated ethical standards and rules for performing human research, in 2018, the first genetically modified babies were born (Lulu and Nana) using a specialized genetic modification technique called CRISPR (pronounced “crisper”). Since genetic engineering of human tissue is not allowed by the scientific community, this experiment was performed in secret and without ethical approval. Against all ethical standards, the researcher responsible allegedly edited the embryos’ DNA to give resistance to HIV, smallpox, and cholera.
The researcher reported some mosaicism, meaning that not all the cells were genetically modified, so it is possible that their resistance to the diseases will be limited. The babies were born healthy, but the long-term impact is not yet known.
Let’s recap some of the key points we have covered in this explainer.
Key Points
- Genetic engineering is the artificial modification of the genome.
- There are many applications of genetic engineering in plants, animals, and medical technology.
- Each application comes with advantages and disadvantages.
- An advantage of genetic engineering is the ability to grow crops with resistance to insects, reducing the need for pesticides.
- A disadvantage of genetic engineering is the possibility of passing on desired genetics to weeds, which would make them difficult to eliminate.
- There are ethical considerations to think about before modifying human DNA.
