Where are ribosomes primarily located within eukaryotic cells?

Ribosomes are primarily located in the cytoplasm and can also be found attached to the endoplasmic reticulum (ER), forming what is known as rough ER. This positioning is crucial for their function in protein synthesis, as ribosomes translate messenger RNA (mRNA) into amino acid chains, which then fold into functional proteins. The association with the ER allows for the efficient processing and transport of proteins that are either secreted from the cell or directed to specific organelles.

Though some ribosomes are found in the mitochondria, which have their own ribosomes due to their endosymbiotic origin, the major sites for ribosomes in eukaryotic cells remain in the cytoplasm and on the rough ER. This understanding highlights the cellular organization and the responsibilities of various cellular components in maintaining homeostasis and function.