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Lesson Video: Applications of Genetic Engineering Biology

In this video, we will learn how to describe some applications of genetic engineering and discuss the advantages and disadvantages of these applications.

15:55

Video Transcript

In this video, we’ll be covering applications of genetic engineering. First, we’ll review recombinant DNA then see how it can be used in treating diseases by producing medications like insulin and modifying organisms such as crops and animals to carry desirable traits. We’ll cover the advantages and disadvantages of these applications. And finally, we’ll go over the ethical and scientific objections to genetic engineering.

Our genetic information is organized as genes in our DNA. These genes control the development of different traits and is what makes humans human and is what makes plants plants. Over the course of human history, we have been manipulating the genetics of different organisms to benefit us. For example, that delicious banana you may have packed for your lunch today was originally a stubby thing full of large black seeds and probably didn’t taste quite as good as today’s banana. You ever wonder why they call an eggplant an eggplant? It’s because they originally were smaller, white, and looked like chicken or goose eggs. Even corn wasn’t fit for popping back then. Apparently, the kernels tasted like potatoes.

All of these examples took thousands of years of selective breeding to get these desired outcomes. That’s a really long time to wait for a snack. With genetic engineering, which is the artificial manipulation of an organism’s genes using biotechnology, this process becomes much easier because we can control which traits we want expressed. So suppose our corn here was being targeted by a particular pest. Rather than breeding the corn plant for resistance, which can take a very long time, we can genetically engineer the plant to contain genes for insect resistance, forcing our little friend here to look elsewhere for a snack. This particular gene, as we’ll see more in detail later in the video, actually comes from a certain species of bacteria.

Often, genetic engineering involves a combination of DNA from at least two different sources, or the bacterial and corn plant DNA in this example, to create new information. This is called recombinant DNA. By genetically engineering this corn plant by inserting the gene for insect resistance, we’re making what’s called a genetically modified organism, or GMO for short. There’s a lot of different applications of genetic engineering. Let’s see some examples of each as they relate to medicine, plants and agriculture, and animals. We’ll start by looking at some medical applications of genetic engineering.

In medicine, genetic engineering can be used to produce different medications to treat various diseases. For instance, in diabetes, the hormone insulin is not produced at sufficient levels to perform its function. Insulin normally signals to the cell to take up glucose. But in those with diabetes, insulin levels are lower, which means that glucose is not properly taken up by the cell and the cell can’t meet its needs for energy. So insulin needs to be provided as a medication in order to overcome this.

One way to produce insulin is to use bacterial cells as microscopic factories to manufacture it. Bacteria normally don’t produce insulin. So to do this, we need to insert the gene for human insulin into the bacterial cell. This is done using recombinant DNA, where the human gene for insulin is inserted into a special type of bacterial DNA called a plasmid. This recombinant DNA can then be transferred inside the bacterium. Once inside the cell, this recombinant DNA can then be expressed to produce the insulin protein which can be extracted and used as medication. This process of producing recombinant DNA containing a gene that’s useful for medicine then transferring it to bacteria is pretty common.

Interferon is a protein that has multiple therapeutic uses, including its use as an antiviral to treat cancer and to treat multiple sclerosis. The process is the same as the insulin example, with the gene for interferon being inserted into bacterial plasmid DNA and then transferred into bacterial cells which manufactured the protein. While the advantages of this technology are clear, one disadvantage is the possibility of antibiotic resistance in bacteria. Plasmid DNA also often contains antibiotic resistance genes. These are used as a selection tool to help scientists grow bacteria that contain recombinant DNA since they will grow in the presence of antibiotics while those without the recombinant DNA will die.

The potential problem here is that this plasmid containing the antibiotic resistance gene can be passed on to other bacteria which may be pathogenic or disease causing. And now this pathogenic bacterium is resistant to a certain antibiotic which can potentially make treating any disease caused by this bacterium more difficult. This is why using this kind of technology is highly regulated to ensure that something like this doesn’t happen.

Now, let’s look at some examples of genetic engineering in plants. Vitamin A deficiency is a major problem in the world that causes over one million deaths per year, primarily in children. One creative way of getting more vitamin A in the diet is to genetically modify the rice plant to produce more of it. Vitamin A biosynthesis is complex, and the rice plant naturally already has some of the genes needed to do this. The missing vitamin A precursors were genetically engineered into the rice plant to allow vitamin A to be produced in the rice grains. This rice produces high levels of vitamin A and as a result is golden in color, which is why it’s often called golden rice. By eating enough golden rice, people are able to meet their dietary requirements for vitamin A. And in this case, rice literally is saving lives.

Another example is one we had seen earlier. Corn is a major crop for the agricultural industry and not only is used to feed you and me, but serves as an important feed for livestock. Corn has multiple pests, including the larva of some species of butterfly or moth, also known as caterpillars. In order to protect the crop from this hungry insect, we can use genetic engineering to introduce resistance. One example of this is a toxin produced by the bacterium, Bacillus thuringiensis, known as the Bt toxin. Scientists have genetically modified the corn plant to include the gene for the Bt toxin. This way the cells of the corn plant produced the Bt toxin. So when our pest eats it, it dies.

Bt toxin is very useful because it’s only activated in the insect gut where the pH is basic. In the mammalian gut, the pH is acidic. So the toxin isn’t activated. As you might imagine, this kind of GMO can lower pesticide use, which can help reduce costs. One of the disadvantages of this technology is that there’s potential that these genes might be passed on to unwanted plant species, such as weeds. In this case, a plant that was normally controlled by the insect population might become out of control.

Another potential disadvantage is reduced genetic diversity. If many farmers are using the same crop with the same genetics throughout the world, indicated here as these orange dots, then this can be a problem if a new disease emerges that this crop is susceptible to. Without genetic diversity, all the crops can be wiped out. Alternatively, if different crops are used that are genetically different from one another, a single disease is unlikely to wipe them out, since some may have genes that offer protection. In this example, let’s say all the blue and orange dots represent crops that are susceptible to a new disease, while the pink dot represents a crop that is naturally protected.

This is what makes genetic diversity in our crops important. These concerns have groups of farmers and other people worried about GMOs. But despite this, many believe that the potential of the technology far outweighs these issues, and scientists are working hard to minimize any of the risks involved. Now, let’s look at some examples of genetic engineering in animals. It’s no secret that salmon are pretty tasty fish. Normally, it takes about 28 to 32 months for farmed Atlantic salmon to reach market size, which is about four to five kilograms. However, in a genetically engineered version of the Atlantic salmon, called AquAdvantage salmon, it can do the same thing in almost half the time.

Atlantic salmon take a break in their development during the fall and winter months when it’s too cold to find the food they would need for their growth. During this time, their expression of growth hormone genes is naturally turned down. In AquAdvantage salmon, a gene was inserted that turns up this growth hormone production all year around. This way, the salmon can grow nonstop and reach market size much more quickly. Another example of genetically modified animals include mice for research purposes. Over the years, many new strains of mice have been developed by genetic engineering. These can be useful in studying the biology of different diseases like cancer, arthritis, diabetes, or any disease really.

However, there’s only so much we can learn from mouse biology. They are in fact mice and we are human, and there’s just so many differences between us, not just physically but on the molecular level as well. So in some cases, mice can be humanized. And I don’t mean engineered to look like humans but rather to carry the human equivalent of certain genes. For example, a mouse can be engineered to contain elements of a human immune system which can be useful to study human diseases. So speaking of humans and genetic modification, is genetic engineering used on humans? In general, no. And this brings us to the topic of the ethical considerations of genetic engineering.

So should we be able to modify human DNA? The medical benefits can be very impressive by opening the door to new treatments for things like heart disease, Alzheimer’s, and cancer. But with advances in these clearly legitimate areas comes the uncertainty of using more aesthetically driven modifications. Should we be able to modify eye color? What about hair color? These kind of modifications might seem trivial. But what about increasing muscle mass or increasing intelligence? These kind of modifications not only change who we are individually, but as a society as well. In addition, applying our knowledge from studies that we’ve done using animals may not translate well into human biology, so we really don’t know the long-term impacts of such modifications.

For this reason, the scientific community has generally abstained from performing genetic engineering on humans. Despite this, in 2018, one researcher went against all of this and performed genetic engineering on human embryos. These embryos resulted in the birth of two genetically modified babies. The embryos were modified to include resistance to HIV infection and to the diseases smallpox and cholera. The babies were born healthy. But the long-term impact has yet to be seen. Now that we’ve seen many different applications of genetic engineering, let’s look at a practice question.

Which of the following would not be an example of an organism modified by genetic engineering? (A) Soybeans have been made to express an enzyme that helps them develop a tolerance to herbicides. (B) A species of corn has had the gene for an insect toxin inserted into its DNA, meaning it has developed some pest resistance. (C) Seedless grapes are sprayed with solutions containing the hormone gibberellin to increase their size. Or (D) a species of tomato has the gene for a specialized salt pump inserted into its DNA, meaning it can grow in very salty soil.

This question is asking us about genetic engineering. So what is that exactly? Let’s clear the answer choices so we have more room to work with. Genetic engineering is the artificial manipulation of an organism’s DNA, usually to produce certain traits that are beneficial. A good example is how bacteria can be genetically engineered to produce the hormone insulin. Insulin is a hormone that controls blood sugar levels. It can do this by signaling to a cell to take up glucose. This glucose can then be converted into energy in the cell and is needed for the cell’s physiology. In the disease diabetes, insulin isn’t produced at sufficient levels, so glucose isn’t taken up and the cell’s energy levels decrease. Without enough energy, the cell can’t perform its functions as effectively.

So in diabetics, insulin needs to be provided as a medication. Insulin is mostly prepared by using genetically modified bacteria. These bacteria have the gene for human insulin inserted into a special piece of bacterial DNA called a plasmid. This can then be transferred into the bacteria. Inside the bacterial cell, the gene for human insulin can be expressed to give rise to the insulin protein. This can then be extracted and used for treatment of diabetes. So in this example, the bacteria have been genetically modified to include the gene for insulin. Now let’s bring the answer choices back and go through them to see which one of them is not an example of genetic engineering.

In the answer choice that states soybeans have been made to express an enzyme that helps them develop a tolerance to herbicides, the fact that they’ve been made to express an enzyme implies that the genetics of the soybean have been artificially manipulated to carry the gene for this enzyme so it can be expressed. So this is an example of genetic engineering. This means that this answer choice is incorrect. In the answer choice that states a species of corn has had the gene for an insect toxin inserted into its DNA, meaning it has developed some pest resistance, the fact that this gene has been inserted into the DNA of the species of corn is artificial manipulation of this organism’s DNA and is an example of genetic engineering. Therefore, this answer choice is also incorrect.

In the answer choice that states seedless grapes are sprayed with solutions containing the hormone gibberellin to increase their size, there is no indication of genetic engineering because that organism’s DNA is not manipulated in any way. A solution containing a hormone is simply applied, which is what is causing the increase in grape size. So this is not an example of genetic engineering, which is what this question is asking us and is therefore correct.

But before we finish, let’s look at the final answer choice just in case. In the answer choice that states a species of tomato has the gene for a specialized salt pump inserted into its DNA, meaning it can grow in very salty soil, here the gene for a salt pump is inserted into the DNA of the tomato, which is artificial manipulation of the organism’s DNA. So this is an example of genetic engineering, and this answer is incorrect.

Now let’s go over some of the key points that we learned in this video. Genetic engineering is the artificial manipulation of an organism’s DNA. There are advantages and disadvantages of genetic engineering. For instance, bacteria can be used to make insulin. However, a disadvantage is the risk of antibiotic resistance being passed on to pathogenic bacteria. Another advantage is the use of golden rice to create nutrient-rich food. However, a disadvantage is if everyone is using the same crop, then this leads to reduce genetic variation. Finally, genetic engineering raises many ethical issues, particularly in the context of using the technology on humans. And this needs to be carefully considered.

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