To determine whether polypeptide chains are attached to small or large ribosome subunits, three experiments can be conducted: SDS-PAGE for band pattern analysis, isoelectric focusing with 2D gel electrophoresis for sequence identification, and cryo-EM for high-resolution structural elucidation. SDS-PAGE can differentiate between subunits based on protein characteristics, while 2D gel allows sequencing for further identification. Cryo-EM offers detailed insights into the architecture of the ribosomal complexes, enabling differentiation based on protein and rRNA composition.