13.1 Genetic Engineering
Learn about genetic engineering, genetically modified organisms and food, and the production of human insulin using recombinant DNA technology.
Learning Objectives
- Define genetic engineering, genome, genetically modified organism (GMO), and transgenic organism.
- Explain the characteristics, advantages, and disadvantages of genetically modified food (GMF).
- Describe examples of genetically modified organisms in plants and animals.
- Sequence and explain the steps involved in the production of human insulin using recombinant DNA technology.
Production of Human Insulin Using Recombinant DNA Technology
A step-by-step molecular process: isolate the human insulin gene, cut a bacterial plasmid, join them using DNA ligase, and transform bacteria to express insulin.
1. Isolate the gene
Human DNA containing the insulin gene is cut using restriction enzymes.
2. Cut the plasmid
A bacterial plasmid is cut using restriction enzymes to open the circular DNA.
3. Join with DNA ligase
The insulin gene is inserted into the cut plasmid and joined by DNA ligase to form a recombinant plasmid.
4. Transform bacteria
The recombinant plasmid is introduced into a host bacterium, producing a transgenic bacterium.
5. Clone and express
The bacterial clone multiplies and synthesises human insulin.
6. Extract and purify
Insulin is extracted from the transgenic bacteria and purified for medical use.
Short Explanation
Key Definitions
Genetic engineering is a gene manipulation technique used to modify an organism's genetic material to produce a new combination of genes. It involves transferring a DNA segment from one organism to another using recombinant DNA technology.
Genome is a complete set of DNA for an organism that includes all of its genes. It contains all the information needed to build and carry out the life processes of an organism.
Genetically modified organism (GMO) is an organism (animal, plant, or microorganism) produced by recombinant DNA technology that contains recombinant DNA.
Transgenic organism is an organism that contains recombinant DNA (DNA transferred from another species).
Examples of GMOs
Genetically modified cow produces milk that lacks \(\beta\)-lactoglobulin, a protein that causes allergies in some children.
Genetically modified goat carries the human gene coding for a blood clotting factor. This factor is secreted into the goat's milk and can be purified to treat haemophilia patients.
Bt corn is corn inserted with a gene from Bacillus thuringiensis to increase resistance against insect pests.
Super Salmon is Atlantic salmon modified by inserting a growth hormone gene from Chinook salmon; it grows at a faster rate, can be produced year-round, and is approved by the FDA as safe for consumption in the USA and Canada.
Freeze-tolerant potato is a potato inserted with a gene from Arabidopsis sp. plant, enabling it to tolerate freezing temperatures and grow well in cold climates.
Genetically Modified Food (GMF)
GMF possesses DNA from other species of plants or animals.
Characteristics of GMF:
- Resistance to pests
- Resistance to herbicides
- Resistance to diseases
- Application in medicine
- Tolerance to heavy metals
Advantages of GMF:
- Overcomes worldwide food shortage by producing high-quality transgenic crops and livestock
- Reduces the cost of food production
- Increases the nutritional value of crops
- Reduces crop-related pest problems
- Reduces the usage of chemical pesticides
- Increases food production, reducing food prices and increasing food availability
Disadvantages of GMF:
- May endanger natural species
- Slight risk that foreign genes (such as antibiotic-resistance genes) could be transferred to humans
- May cause unknown adverse effects on human health and genetic material
Production of Insulin by Genetic Engineering
Previously, insulin was extracted from the pancreases of cattle or pigs. Nowadays, it is produced commercially via recombinant DNA technology using Escherichia coli.
Other products of genetic engineering include hepatitis B vaccine, blood clotting factors, and growth hormones.
Try to Answer First
Answer in your mind, then press “Check Answer”.
What is the definition of a transgenic organism?
Name the two enzymes involved in the construction of a recombinant plasmid for insulin production and state their functions.
State two potential disadvantages or concerns related to genetically modified food (GMF).
Common Mistakes
- Confusing the roles of restriction enzymes and DNA ligase: students often think DNA ligase cuts DNA and restriction enzymes join DNA, whereas restriction enzymes cut DNA at specific sites and DNA ligase joins DNA fragments together.
- Confusing a plasmid with the whole bacterial chromosome: a plasmid is a small circular piece of DNA distinct from chromosomal DNA that acts as a cloning vector.
- Mixing up the terms GMO and transgenic organism: while both contain recombinant DNA, students often forget that a transgenic organism specifically carries a foreign gene introduced from a different species.
- Assuming insulin is directly secreted as medicine by bacteria without processing: the insulin must be extracted from the transgenic bacterial culture and purified before it can be used by patients.
Concept Misunderstandings
Genetic engineering only benefits crop plants.
Genetic engineering is applied across microorganisms, plants, and animals. Examples include producing human insulin in bacteria (E. coli), clotting factors in goats, allergy-free milk in cows, and faster-growing salmon.
Insulin for diabetics today is still mostly extracted from slaughtered cattle and pigs.
While it was historically obtained from animal pancreases, modern insulin is commercially produced via genetic engineering using transgenic E. coli, which produces human insulin identical to natural human insulin.
Genetically modified food has no documented advantages for consumers or the environment.
GMF provides documented benefits such as increased nutritional value, reduced reliance on chemical pesticides, decreased production costs, and increased food availability.
Summary
- Genetic engineering modifies an organism's genetic makeup by transferring DNA segments using recombinant DNA technology to produce GMOs and transgenic organisms.
- In agriculture, it enhances crops with traits like pest resistance (Bt corn) and frost tolerance (Arabidopsis-modified potato), though it poses debated risks such as threats to natural species and gene transfer.
- In medicine, recombinant DNA technology inserts target human genes into bacterial plasmids using restriction enzymes and DNA ligase.
- Transgenic bacteria (E. coli) commercially produce therapeutic proteins such as human insulin, growth hormone, and blood clotting factors.
Short Activity
Objective: test your understanding of genetic engineering, GMOs, GMF and insulin production.
A. Objective Quiz
Which enzyme is used to join the human insulin gene into a cut bacterial plasmid during the production of a recombinant plasmid?
What is the source of the growth hormone gene inserted into the Atlantic salmon to produce the fast-growing Super Salmon?
B. Fill in the Blanks
A complete set of DNA for an organism that includes all of its genes is known as a .
The small circular DNA found in bacteria that is used as a cloning vector in genetic engineering is called a .
C. Matching / Drag and Drop
Drag each organism to its correct modification or application. On a phone, tap a choice first, then tap the matching box. Tap the Answer Choices area to return a selected item.
C. Match the Organism to Its Modification or Application
Write the correct organism next to each modification or application.
| Modification / Application | Organism / Product |
|---|---|
| 1. Produces milk lacking \(\beta\)-lactoglobulin to prevent allergies in children | |
| 2. Produces milk containing human blood clotting factor to treat haemophilia | |
| 3. Possesses a bacterial gene that confers resistance against insect pests | |
| 4. Synthesises human insulin commercially for diabetes mellitus patients |
Answer choices: Genetically modified cow • Genetically modified goat • Bt corn • Transgenic E. coli
