In prokaryotes cells, ribosomes are associated with the plasma membrane of the cell. They are about 15 nm by 20 nm in size and are made of two subunits – 50S and 30S units which when present together form 70S prokaryotic ribosomes. Ribosomes are the site of protein synthesis. Several ribosomes may attach to a single mRNA and form a chain called polyribosomes or polysome. The ribosomes of a polysome translate the mRNA into proteins.
Inclusion bodies: Reserve material in prokaryotic cells is stored in the cytoplasm in the form of inclusion bodies. These are not bounded by any membrane system and lie free in the cytoplasm. e.g. phosphate granules, cyanophycean granules, and glycogen granules. Gas vacuoles are found in blue-green and purple and green photosynthetic bacteria.