Q.58 Given below are two statements:
Statement I: In transgenic plants developed by prokaryotic expression systems, the expression of transgene is
very high.
Statement II: Eukaryotic protein expression system is of limited use as the expression is very low in
transgenic organisms.
In the light of above statements, choose the most appropriate answer from the options given below:
1. Both Statement I and Statement II are correct
2. Both Statement I and Statement II are incorrect
3. Statement I is correct but Statement II is incorrect
4. Statement I is incorrect but Statement II is correct
Transgenic Plants Expression: Prokaryotic vs Eukaryotic Systems
Prokaryotic expression systems like bacteria yield high transgene expression due to rapid growth and simple machinery, but they often fail for eukaryotic plant proteins needing modifications. Eukaryotic systems, while more complex, achieve proper folding and activity in transgenic plants despite tunable expression levels.
Correct Answer
Option 2: Both Statement I and Statement II are incorrect
Statement I wrongly claims very high transgene expression in prokaryotic systems for transgenic plants, as bacterial systems like E. coli often misfold plant proteins lacking glycosylation. Statement II incorrectly states eukaryotic systems have very low expression; plant systems (eukaryotic) routinely produce high yields with proper modifications.
Option Breakdowns
Option 1: Both Correct (Incorrect)
Assumes prokaryotic systems excel in plants and eukaryotic ones underperform universally.
Prokaryotes offer speed but poor post-translational modifications essential for plant transgenes.
Option 2: Both Incorrect (Correct)
Prokaryotic expression suits microbes but not complex plant proteins; eukaryotic systems like yeast or plants provide better fidelity and scalable expression.
Eukaryotic plant systems express transgenes effectively for commercial traits like Bt toxin.
Option 3: I Correct, II Incorrect (Incorrect)
Overstates prokaryotic advantages; bacterial inclusion bodies require refolding for plant proteins.
Eukaryotic systems handle introns and modifications correctly.
Option 4: I Incorrect, II Correct (Incorrect)
While I is wrong, II fails as eukaryotic systems (e.g., Agrobacterium in plants) achieve high expression, not limited low levels.
Expression Systems Comparison
| System | Strengths | Limitations | Plant Transgene Suitability |
|---|---|---|---|
| Prokaryotic (E. coli) | High yield, fast, cost-effective | No glycosylation, misfolding | Low for eukaryotic proteins |
| Eukaryotic (Yeast/Plants) | Proper folding, modifications | Slower, complex regulation | High for functional plant transgenes |
Prokaryotic systems excel for simple bacterial proteins but underperform for plant transgenics needing eukaryotic processing.
