By the end of this lesson
- Define the term transgenic.
- Identify transgenic organisms from examples.
- Distinguish transgenic organisms from selectively bred organisms.
BIG QUESTION
Is a bacterium that makes human insulin still just a bacterium?
It is transgenic: it contains a gene that came from another species.
Meaning of transgenic
A transgenicDescribes an organism that contains a gene transferred from a different species. organism contains genetic material transferred from a different species. The transferred gene is called a transgeneA gene transferred from one species into another..
This works because the genetic codeThe way base triplets in DNA code for amino acids; it is universal, so the same triplets code for the same amino acids in almost all organisms. is universal: the same base triplets code for the same amino acids in almost all organisms.
Examples
Bacteria with the human insulin gene, Bt maize with a bacterial gene and golden rice with genes from other species are all transgenic.
Transgenic animals, such as sheep or goats that produce human proteins in their milk, also exist.
What is not transgenic
A selectively bred variety is not transgenic, because its alleles come from the same species by normal breeding.
Genetic modification that changes or moves a gene within one species is genetically modified but not transgenic, because no other species is involved.
Transgenic or not?
Ask where the genetic material came from.
| Organism | Source of new genetic material | Transgenic? |
|---|---|---|
| Bacterium making human insulin | Human (different species). | Yes. |
| Bt maize | Bacterium (different species). | Yes. |
| High-yield wheat from selective breeding | Same species, normal breeding. | No. |
Language that earns precision
- transgenic
- Containing genetic material transferred from a different species.
- transgene
- A gene transferred from one species into another.
- genetic code
- The way base sequences code for amino acids; shared by almost all organisms.
Common misconceptions
Claim: All GM organisms are transgenic.
Correction: Only those with genetic material from a different species are transgenic.
Claim: Selectively bred organisms are transgenic.
Correction: Selective breeding uses alleles of the same species.
Claim: A transgenic organism becomes a new hybrid species.
Correction: It stays the same species with one or a few added genes.
Match the answer to the command word
Use the full phrase: transfer of genetic material from one species to a different species.
Identify the donor species and the recipient species in any example.
Recall, apply, then justify
What is meant by the term transgenic?
Hint
Species.
Suggested marking points
- Transfer of genetic material from one species to a different species.
Explain why a wheat variety produced by selective breeding is not transgenic.
Hint
Where do the alleles come from?
Suggested marking points
- Its alleles come from wheat / the same species.
- No genetic material has been transferred from a different species.
Explain why a human gene inserted into a bacterium can produce a human protein, and why the bacterium is described as transgenic.
Planning hint
Universal code and species.
What a strong design includes
- The genetic code is universal / the same in humans and bacteria.
- The base sequence of the human gene codes for the same amino acids.
- So the bacterium makes the same protein as human cells.
- The gene came from a different species (human).
- So the bacterium is transgenic.