UPSC Prelims 2013 Q5: Science & Technology – Biotechnology & Genetics
Recombinant DNA technology (Genetic Engineering) allows genes to be transferred
1. Across different species of plants
2. From animals to plants
3. From microorganisms to higher organisms
Select the correct answer using the codes given below.
- (a) 1 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (d) 1, 2 and 3
Explanation
Recombinant DNA technology
Genetic engineering cuts a gene out of one organism and puts it into another.
Because DNA is the same chemical in all life, genes can move between any two species.
| Transfer | Possible? | Example |
|---|---|---|
| 1. Across different species of plants | Yes | Golden Rice: genes from daffodil and maize |
| 2. From animals to plants | Yes | Fish antifreeze gene tried in tomato |
| 3. From microorganisms to higher organisms | Yes | Bt cotton: gene from the bacterium Bacillus thuringiensis |
Tools of the technology:
| Tool | Role |
|---|---|
| Restriction enzymes | 'Molecular scissors' that cut DNA |
| DNA ligase | 'Glue' that joins DNA |
| Vector | Carrier of the gene, such as a plasmid |
| Host | The organism that receives the gene |
Human insulin is made by bacteria that carry the human gene.
Answer: (d) 1, 2 and 3.
Why each option is right or wrong
- (a) Incorrect. Genes can also move from animals to plants and from microorganisms to higher organisms.
- (b) Incorrect. Transfer across plant species is also possible.
- (c) Incorrect. Transfer from animals to plants is also possible.
- (d) CORRECT. Recombinant DNA technology allows all three kinds of transfer.
Key point
Recombinant DNA: genes can be moved between any species using restriction enzymes, ligase and vectors (Bt cotton, Golden Rice, human insulin from bacteria).
Remember
Genetic engineering crosses all species barriers.
Common mistakes
- Thinking genes can move only between related species.
- Confusing genetic engineering with ordinary cross-breeding.
- Forgetting the tools: restriction enzymes and plasmids.
Exam tip
DNA is a universal code. That is why any-to-any transfer works.
Sources
- NCERT Class XII — Biology (Biotechnology: Principles and Processes)
- NCERT Class XII — Biology (Biotechnology and its Applications)