Question

a diagram of a cell is shown below.
proteins are synthesized in which numbered organelle?
○ 1
○ 2
○ 3
○ 4

Explanation:

To determine where proteins are synthesized, we recall cell organelle functions:

• Organelle 1 (mitochondria) produces energy (ATP), not synthesize proteins.
• Organelle 2 (Golgi apparatus) modifies/sorts proteins, not synthesize them.
• Organelle 3 (rough endoplasmic reticulum or ribosomes associated with it) is the site of protein synthesis (ribosomes on ER or free in cytoplasm make proteins).
• Organelle 4 (nucleolus) is involved in ribosome production, not direct protein synthesis.

Thus, protein synthesis occurs in organelle 3.

Answer:

3 (the option corresponding to the organelle where protein synthesis occurs, typically the rough ER/ribosomes, labeled as 3 in the diagram)