4BI1
Genetic Engineering
Use of Biological Resources · 6 question types
Exam Frequency Analysis
Past paper frequency (2018 to 2024)
This topic accounts for approximately 10% of your exam marks.
increasing
Medium
Increasing10%
Insulin production by bacteria and GM crops are growing in exam frequency.
Genetic engineering and selective breeding both aim to produce organisms with useful new traits. They achieve this in very different ways.
| Feature | Selective breeding | Genetic engineering |
|---|---|---|
| What it does | Combines existing alleles already in the species through generations of choosing parents | Inserts specific genes (from any species) directly into the DNA |
| How long it takes | Many generations (often years to decades) | Fast at the lab stage (days to weeks for bacteria) |
| Source of new traits | Alleles already present in the species, brought together by breeding | Genes from any organism, even different kingdoms |
| Precision | Imprecise: many genes are shuffled together at each cross, and offspring inherit a mix | Very precise: only the specific gene wanted is moved |
| Risk of unintended changes | Lower (genes from same species are well-tested) | Higher in principle (foreign DNA in new context can have unexpected effects) |
| Public acceptance | Widely accepted (10 000 years of tradition) | Controversial; many people are wary of "unnatural" GM food |
| Examples of products | Modern wheat, dairy cattle, dog breeds | Insulin-producing bacteria, Bt crops, golden rice |
The two techniques can be combined. Genetic engineering can introduce a useful gene; selective breeding can then improve other characteristics over generations.