| Unit IV Objectives |
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The students will learn:
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Sparked by the understanding of how cells and living processes work, biotechnology presents us with new ideas to:
"New" biotechnology began to develop in the 1970s especially with:
Keep in mind that biotechnology is a broad term for a number of methods which manipulate cells and genes. However, it is beyond the scope of this unit to consider them all. We shall restrict our focus to what is commonly known as genetic engineering or recombinant DNA (rDNA) techniques and also take a second look at fermentation technology.
How would you like tastier French fries, low in fat and calories? What about tomatoes that are juicy, red, flavorful and remain firm and fresh as well? If you were a farmer, what would you say about crops resistant to pests, diseases, frost and drought? And gives high yields as well? Suppose you suffered from diabetes, or cancer and you could get a cure?
How can biotechnology do all this? Recall that all organisms, whether bacteria or the extinct dinosaur, use the same molecule -- DNA -- to store genetic information. Since the genetic language is universal, it is possible to cut and paste pieces of genes. Actually, genes being "cut" and "glued" together again can happen naturally at random, when our cells divide to make more cells and DNA is being produced.
Scientists can also do this intentionally. This is known as recombinant DNA (rDNA) technology or genetic engineering. The idea is to persuade the original DNA molecule to adopt and integrate a new gene so that it yields a new trait or product.
With recombinant DNA technology, scientists can do what nature has not done:
Let us look at two ways in which this technology is being used:
First, desired genes can be directly inserted into the cells of host plants or animals.
Inserted genes usually make something happen. For example, a gene can be introduced into a crop which will produce a substance toxic to targeted pests when eaten. The crop is then said to be pest-resistant.
Inserted genes can also stop something from happening, for example, a gene has been introduced into a tomato that prevents it from becoming soft while ripening. This allows the fruit to stay firm, making it easier to transport.
Second, desired genes are introduced via another organism.
Very often, it is difficult or too expensive to directly introduce genes into a complex organism. Scientists have a technique to add these genes to bacterial or viral cells instead, and hope that some of them will adopt the new genes. Bacteria multiply very quickly, so scientists can find those that have adopted the new gene and breed them separately in a bacteria culture. The result: the new gene has been cloned, i.e. the bacteria create copies of themselves.
Recall from Unit I that genes are like recipes for specific products. So if we are able to clone the gene, we can mass produce desired products. One example of this is the pioneering production of human insulin, a hormone used to treat diabetes. This was the first commercial application of recombinant DNA technology in 1977. Bacteria with the new gene started to produce insulin, which can then be easily extracted and purified.
Today, recombinant DNA technology has many applications, especially in agriculture and medicine.
In biotechnology, the term fermentation is actually used to refer to the process of generating large numbers of microbes such as bacteria. The idea is that when these microbes are placed in a suitable environment, or fermenter, where nutrients are kept adequate, they will multiply. This is the process of cloning microbes. Greater numbers of microbes can produce more desired products.
Fermentation may seem rather unsophisticated when we think of baking bread or brewing beer. However, scientists are finding new applications for this age-old technology. One such application is the production of biofuels. These are made from plants.
Fermentation of some plants produce alcohol, just like in wine-making. For example, sugar cane and corn when fermented produce the alcohol called ethanol. Ethanol is a biofuel that can be used as a substitute for gas. In Brazil, all the cars run on ethanol or a petroleum-ethanol mixture.
Another application of fermentation is in the manufacture of bioplastics. Bacteria that make plastics similar to polyester are added to huge fermentation vats where they feed on crops such as sugarcane. The plastics that are created as a by-product can be used to make shampoo bottles and disposable razor holders.
However, sometimes, it is not so much the products of fermentation that is sought, but the microbes themselves. The production of the insulin hormone combines both genetic engineering with the fermentation process.
As discussed earlier, the human gene responsible for insulin production is introduced into bacteria. These bacteria are then allowed to multiply in a vat containing nutrients. As a result, the bacteria containing the gene are cloned and insulin can be produced in large quantities.
The limitations of using fermentation biotechnology in these new applications are essentially the same as those in old applications. Despite the variety of products that can be made, fermentation processes depend on the work of those single-celled organisms like bacteria and yeast, which live in specific environments.
Perhaps one of the basic reasons for concern is simply the speed of change. Selective breeding also involves the manipulation of nature but the results take several years to show. In the time taken, whole societies can adapt and may even adopt the process as a part of their culture as discussed in Unit II.
Recombinant DNA technology, however, can offer results almost immediately. Thus, there is a sense that we lack control and security. Indeed, with old biotechnology, anyone can apply it and control the process. With new biotechnology, this responsibility lies almost exclusively with scientists, industrialists and policymakers.
Further, since new biotechnology often involves bacteria and viruses, there is a concern that accidental release may be difficult to deal with since they can multiply very quickly and can be a risk to health.
Scientists are aware of the health risks since they deal with the microbes in their work. Often, they try to make use of microbes which are commonly found and which they know a lot about.
How about genetically modified foods? Rigorous procedures would have to be in place to ensure quality and safety to consumers. In general, biotechnology is a highly controlled process with genetic modifications introduced one at a time and outcomes systematically monitored.
Regulation of quality and safety are conducted by government agencies, corporations, and, among the scientific community. We can say this is an "external" means of regulating biotechnology.
But are we treating organisms as simply a bunch of cells to be manipulated? This is an ethical question that has no easy or straightforward answers.
Microorganisms such as yeast and bacteria play a very useful role in our lives. Many bacteria even live in animals and humans, helping in the digestive system. They are fundamental to the ecosystem, breaking down dead plants and animals, to produce useful, rich soil that sustains more growth. Thus, fermentation biotechnology may be regarded as an extension of the role of these microbes in nature.
On the other hand, is it right to alter the genetic makeup of a plant, an animal, or even a bacterium even if it is safe? Should we give these organisms genetic recipes that they never had, especially if they were genes from another species?
There are many factors to consider such as the social and economic impacts. However, one important way of answering these questions is to decide if there is a real need for the product. For instance, suppose we could do it, do we need a tomato that tastes like chicken? Probably not. But what if altering a plant or bacterium genetically can produce new medicines which were unavailable? Or what if there is a chance that new biotechnology can offer environmentally more friendly resources like biofuels and biodegradable plastics? Are these worth the long term impacts that are often unknown?
Biotechnology -- old and new -- is a very dynamic concept that can have as many applications as the mind can imagine. Already, many products are on the market. In understanding what biotechnology means, we can make better decisions for ourselves and all that is in our environment.
| In the Market: Biotech Old and New | |
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| Today | Tomorrow |
| Baby whole carrots | Seedless mini-melon |
| Tomatoes that stay fresh up to two weeks | Sweeter peas and peppers |
| High-Laurate Oil a raw material used in soaps, detergents and cocoa butter replacement fats |
Low-Saturate Oil a healthier salad and cooking oil from rapeseed plants |
| Bst-stimulated Milk A growth hormone called Bst has been introduced in cows to stimulate milk production. A gene with the recipe for Bst was inserted in bacteria. |
Colored Cotton color-producing genes from bacteria are introduced in cotton genes. This will mean fewer dyes are needed, reducing environmental pollution. |
| Eggs vaccinated while still in the shell against a common virus | Salmon faster-growing salmon |
| Insulin a hormone for diabetics, who are unable to produce the hormone to break down sugar. Produced by genetically-engineering bacteria. |
Tissue Plasminogen Activator (TPA) a natural human protein that dissolves blood clots, used when a heart attack occurs, allowing blood to flow. Used currently in hospitals but patients may be able to use it themselves one day. |
| Hepatitis B Vaccine | AIDS Vaccine |
| AspireTM a biofungicide used on citrus fruits, berries, and grapes to prevent postharvest rot. It is a naturally occurring yeast, harmless to non-targeted organisms. |
Insect-protected corn and potato genetically improved plants to control the European corn borer and the Colorado potato beetle |
| Methane gas a biogas that can be obtained from microbial fermentation of domestic, agricultural, and industrial wastes |
WHAT DO YOU THINK? |
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| Purpose of Activity |
Use this activity to discuss some reasons to make changes in organisms and to explore the need for genetic changes. |
Bring to class as many varieties of tomatoes as are available: Bring in some that are very ripe and "mushy" and others that are still firm.
Show the students the various tomatoes. Ask the students the following questions:
For instance, the big red tomatoes are sliced and used in hamburgers. Cherry tomatoes are great bite sizes in salads. Perhaps people want yellow tomatoes for a change of color.
Have the students feel the ripe, mushy tomatoes and the firm but less ripe ones.
Explain that unripe tomatoes contain pectin that keeps them firm. Pectin is commonly found in jams and jellies. When tomatoes ripen, they turn red and become tasty. They also turn soft because the pectin gets "eaten up."
To make the tomato easy to transport and remain attractive, scientists have found a gene or instructions that tell the tomato to stop eating up the pectin.
Slice some tomatoes and encourage students to taste them.
Share with students that they have just come up with various reasons why people might want to make changes in tomatoes and other organisms. Plant breeders and scientists try to develop new varieties of tomatoes and other crops to respond to people's needs and interests. Sometimes, they also introduce new genes into bacteria to produce different items like the hormone insulin.
| Materials |
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any art supplies available, e.g. paints, brushes, crayons, ink markers, tissue, glue, scissors, paper |
| Purpose of Activity |
Use this activity to demonstrate the purpose of manipulating genetic change: to produce organisms with desired traits and to discuss why these traits are important. |
Divide the students into dyads or pairs.
Assign each team one of the tasks from the "Task Table." Ask the students to discuss what features or adaptations an animal might need for the task given. Some examples are given below.
Allow each team to briefly report their conclusions.
Next, tell each team that they will be given a set of tasks: a habitat task, a food task, and a transportation task. Each team will create an animal that can complete their three tasks. (Please refer to the "Task Table." The set can be a combination of any three.)
| Tasks | Possible Adaptations |
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| Feeds off seaweed or water plants | Large mouth; large front teeth to tear plants or smaller back teeth to grind soft food. |
| Lives on land, but feeds off water life (fish, shellfish) | Paws adapted for swimming (webbed feet) to catch prey. |
| Hunts at night from the air | Wings with dispersed feathers at the end of the wings to reduce sound, large eyes to gather all possible light. |
Each team can select art supplies from what is available to render pictures, models, or representations of their creatures.
Explain that these various characteristics are part of what we look for in biotechnology. For example, in vegetable plants, we look for the most desirable traits of various kinds of vegetables and breed them to produce those characteristics. For instance, in the previous activity, we looked at the traits of different kinds of tomatoes and saw that different varieties are different uses.
We can also combine traits. We use the trait of one variety that ripens early in the season, choose the trait of another variety to have a thicker skin, and the trait of a hearty flavor from another.
With assistance, we produce a tomato plant that would be suitable for short growing seasons (possibly in the far northern areas of the continent), that has a durability to be kept for longer periods of time in the home, and, yet possess the taste we expect from tomatoes. We have done the same thing with many plants, fruits, vegetables, livestock and domestic pets.
| Task Table | ||
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| Habitat Task | Food Task | Transportation Task |
| Lives in marsh or swampy areas | Hunts at night from the ground | Has no feet or paws--moves by slithering |
| Builds nests of grasses | Scavenges for food from what animals have left behind | Moves very slow--eats only small insects that come close |
| Lives in deep, open water; feeds on small fish | Eats insects but lives on the ground | Moves from place to place by flying short distances |
| Lives on the open plain | Eats small plants close to the ground | Moves from place to place by hopping |
| Lives in rocky areas with little vegetation | Lives in treetops, eats only insects | Moves from place to place only at night |
| Lives in high altitudes | Lives underground, eats plant roots | Wings to travel between home and food |
| Lives in very cold climates | Hunts in daylight from the air | Uses fins to move around |
| Lives in forests on the ground | Hunts only small rodents that live on the high plains. | Spends a lot of time in water, but lives on land |
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| Purpose of Activity |
Use this activity to sum up the unit and for evaluation. |
Have each student choose a specific plant or animal. Students may also work in pairs of small groups.
Have students decide on one trait they would like to change or adapt in the plant or animal. Using any of the art supplies, have students report on the change of this trait in the plant or animal.
Tell the students that their report:
Have each student present their project to the full group.
This activity can serve as an evaluation of the unit. Evaluation can be based on how thoroughly each student or team addresses the considerations you emphasized in the course of the unit.
This activity is highly variable to your specific instructions through the unit, and the directions to the students can and should reflect the focus you had.