What is the total ribosomal subunit size in eukaryotes?

In eukaryotes, the total size of the ribosomal subunits is classified as 80S. Ribosomes are composed of two subunits: the larger subunit, which is 60S, and the smaller subunit, which is 40S. The "S" stands for Svedberg units, a measure of the rate of sedimentation during centrifugation, which reflects both the size and shape of the ribosomal particles.

The designation of 80S for eukaryotic ribosomes indicates that when the two subunits come together for protein synthesis, they form a ribosome that sedimentarily behaves as a single entity weighing 80S. This is a critical aspect of eukaryotic biology since ribosomes are essential for translating mRNA into proteins, a fundamental process in cellular function and growth.

In contrast, prokaryotic ribosomes are classified as 70S, made up of 50S (large subunit) and 30S (small subunit). Understanding the distinction between these ribosomal sizes is important in various biological contexts, including antibiotic targeting, as some antibiotics specifically inhibit prokaryotic ribosomes without affecting eukaryotic ribosomes due to their structural differences.