Answer:
Ribosome, a large-number-of-ribosomes-present particle that is essential for protein synthesis in all living cells. Prokaryotic and eukaryotic cells both include free ribosomes, and eukaryotic cells also contain ribosomes that are affixed to the endoplasmic reticulum membranes. George E. Palade, an American cell scientist of Romanian descent, first identified the microscopic particles that would later be known as ribosomes in 1955. He discovered that these particles were commonly connected to the rough endoplasmic reticulum of eukaryotic cells.
Step-by-step explanation:
Cells have a remarkable number of ribosomes. For instance, a single eukaryotic cell that is actively reproducing may have up to 10 million ribosomes. As many as 15,000 ribosomes—a prokaryote—can be found in the bacterium Escherichia coli, accounting for as much as one-fourth of the mass of the cell. Depending on the cell type and variables like whether the cell is resting or reproducing, the size of the ribosomes within cells varies. The best-characterized example, the typical ribosome of E. coli, has a diameter of roughly 200 angstroms (or 20 nm).