UPSC Prelims 2001 Q123: Science & Technology – Biology
Which of the following cell organelles play the most significant role in protein synthesis?
- (a) Lysosome and Centrosome
- (b) Endoplasmic reticulum and Ribosome
- (c) Golgi apparatus and Mitochondria
- (d) Lysosome and Mitochondria
Answer: (b) Endoplasmic reticulum and Ribosome
Explanation
Cell organelles most important in protein synthesis
| Organelle | Main role |
|---|---|
| Ribosome | Site of protein synthesis — reads mRNA and joins amino acids |
| Endoplasmic reticulum (rough) | Carries ribosomes; folds and transports proteins |
| Golgi apparatus | Modifies and packages proteins |
| Mitochondria / lysosome | Energy (ATP) / digestion |
Proteins are made on ribosomes, many of which sit on the rough endoplasmic reticulum. Together they form the main protein-making system of the cell. The Golgi only packages proteins after they are made.
Answer: (b) Endoplasmic reticulum and Ribosome.
Why each option is right or wrong
- (a) Incorrect. Lysosomes digest material; centrosomes help in cell division.
- (b) CORRECT. Ribosomes on the rough ER make proteins.
- (c) Incorrect. The Golgi packages and mitochondria supply energy; neither makes proteins.
- (d) Incorrect. Lysosomes digest and mitochondria make ATP.
Key point
Ribosomes are 'protein factories'; mitochondria are 'powerhouses'; lysosomes are 'suicide bags'.
Remember
Protein synthesis: ribosomes and rough ER.
Common mistakes
- Choosing the Golgi, which only packages proteins.
- Choosing mitochondria because they supply energy.
- Forgetting that rough ER is rough because of ribosomes.
Exam tip
Protein made on ribosomes → processed in ER → packed in Golgi.
Sources
- NCERT Class XI — Biology, chapter 'Cell: The Unit of Life'
- NCERT Class IX — Science, chapter 'The Fundamental Unit of Life'