Both prokaryotic and eukaryotic cells contain which of the following structures?

Both prokaryotic and eukaryotic cells contain ribosomes, which are essential for protein synthesis. Ribosomes are the complexes made of ribosomal RNA (rRNA) and proteins that translate messenger RNA (mRNA) into polypeptides, thus playing a critical role in the cellular function of all living organisms.

In prokaryotic cells, ribosomes float freely in the cytoplasm, while in eukaryotic cells, they can be found both free in the cytoplasm and attached to the endoplasmic reticulum, contributing to the rough ER structure. Despite the differences in cell type, the fundamental process of synthesizing proteins using ribosomes remains conserved across both domains. This highlights the essential role ribosomes play in the life of the cell, serving as a common structure crucial for cellular function, irrespective of the complexity of the organism.

Other structures mentioned, such as the nucleus, mitochondria, and chloroplasts, are specific to eukaryotic cells. Prokaryotic cells lack a nucleus and membrane-bound organelles like mitochondria and chloroplasts, which are important for energy production and photosynthesis, respectively.