Ribosomes may be attached to the cytoplasmic side of which structures?

1. Ribosomes appear either as free clusters called polyribosomes or as single dots floating in the cytoplasm. 2. Others are attached to the cytoplasmic side of the plasma membrane. 3. Others again attach to the cytoplasmic side of the endoplasmic reticulum and to the outer membrane of the nuclear envelope. 4. Thylakoids and cristae are internal folds of chloroplasts and mitochondria, which is not where attached ribosomes are described. 5. The attachment sites are the plasma membrane and the endoplasmic reticulum. 6. An attached ribosome faces the cytoplasm rather than the lumen, which is why the new chain has to be transferred inward. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 4 "Cell Structure", section 4.3 Eukaryotic Cells_