How many subunits compose the ribosomes of eukaryotic cells?

In eukaryotic cells, ribosomes are composed of two subunits: the large subunit and the small subunit. Specifically, the large subunit is designated as 60S, while the small subunit is 40S, making the complete ribosome a 80S unit in terms of sedimentation coefficient. This structure is essential for protein synthesis, as the two subunits come together during the translation process to facilitate the linking of amino acids in the correct sequence dictated by the mRNA.

Understanding the composition of ribosomes is crucial because it highlights differences between prokaryotic and eukaryotic ribosomes, which can have implications for antibiotic action and the study of cellular processes. In prokaryotic cells, for example, ribosomes consist of a 70S unit made up of 50S and 30S subunits. This distinction is important in microbiology, especially in targeting bacterial infections without harming human cells.