The smaller (40S) of ribosome combines with larger subunit (60S) in the presence of Mg2+ ion to form _ particle.

Explanation

The S in the ribosomal subunits stands for svedberg units. It represents the different sedimentation rates of the ribosomes during centrifugation. The 60s and 40s ribosomal subunits join to form an 80S ribosome found in eukaryotes.