Where are free ribosomes located in the cell?

• A. Attached to the endoplasmic reticulum
• B. In lysosomes
• C. Within mitochondria
• D. Spread throughout the cytosol

Answer: (D)

Ribosomes come in two main locations, and the one that describes free ribosomes is the cytosol. Free ribosomes float freely in the fluid part of the cytoplasm and primarily synthesize proteins that function within the cytosol or are destined for other cellular compartments after translation. They are not attached to membranes. In contrast, ribosomes bound to the rough endoplasmic reticulum make proteins that are secreted, inserted into membranes, or shipped to lysosomes. Lysosomes themselves don’t contain ribosomes, and mitochondria have their own ribosomes separate from the cytosolic pool. So the characteristic location for free ribosomes is spread throughout the cytosol.