By the end of this lesson
- Describe how a transgenic animal can produce a human protein.
- Explain why cloning is used for transgenic animals.
- Evaluate the benefits and concerns of this technology.
BIG QUESTION
Can a goat make a human medicine?
A human gene inserted into a goat can be expressed in its milk, and cloning can copy that goat.
Producing a transgenic animal
A human gene for a useful protein is inserted into the DNA of a sheep or goat embryo, often next to a gene control sequence that is active only in the mammary glandsGlands in female mammals that produce milk..
The animal becomes transgenicDescribes an organism that contains a gene transferred from a different species. and produces the human protein in its milk, from which it is extracted and purified. Examples include proteins used to treat blood-clotting or other disorders.
Why clone them?
Producing a transgenic animal is difficult, and few embryos take up and express the gene. Once one succeeds, cloneAn organism or cell that is genetically identical to its parent; cloning is producing such copies. can produce many genetically identical copies.
Every clone carries the human gene and can produce the protein, whereas sexual reproduction would pass the gene to only some offspring.
Benefits and concerns
Milk can be collected without harming the animal, and large amounts of protein may be made more cheaply than by some other methods.
Concerns may include animal welfare, health problems in clones, low success rates and ethical objections to using animals in this way.
Producing human proteins
Each method suits different proteins.
| Feature | GM bacteria | Cloned transgenic animals |
|---|---|---|
| Where protein is made | In bacterial cells in a fermenter. | In milk from mammary glands. |
| Suitable proteins | Simpler proteins such as insulin. | More complex human proteins. |
| Main concern | Contamination and purification. | Animal welfare and low success rates. |
Language that earns precision
- transgenic animal
- An animal containing a gene from a different species.
- mammary glands
- Glands that produce milk.
- human protein
- A protein coded for by a human gene, used for example as a medicine.
Common misconceptions
Claim: Drinking the milk gives the medicine.
Correction: The protein is extracted and purified before use.
Claim: Offspring from normal breeding all inherit the gene.
Correction: Sexual reproduction may pass it to only some offspring; cloning copies it to all.
Claim: The animal becomes partly human.
Correction: It is a sheep or goat containing one human gene.
Match the answer to the command word
Link the gene to protein production in milk, then explain why cloning gives many animals with the gene.
Balance medical benefits with welfare and ethical concerns.
Recall, apply, then justify
Explain why transgenic sheep that produce a human protein are cloned rather than bred normally.
Hint
Which offspring get the gene?
Suggested marking points
- Cloning produces offspring genetically identical to the transgenic sheep.
- So all offspring carry the human gene (normal breeding may not pass it to all).
Describe how a human protein is obtained from a transgenic goat.
Hint
Where is it produced?
Suggested marking points
- The goat produces the human protein in its milk.
- The protein is extracted / purified from the milk.
Evaluate the use of cloned transgenic animals to produce human proteins for medicine.
Planning hint
Medical, practical and ethical points.
What a strong design includes
- Human proteins can be produced for patients who need them.
- The protein is collected in milk without killing the animal.
- Cloning gives many animals all carrying the gene.
- Producing the first transgenic animal and cloning have low success rates.
- Clones may have health or welfare problems.
- Some people object on ethical grounds; overall value may depend on the medicine needed.