The 70S ribosome is a type of ribosome found in prokaryotic cells, such as bacteria. It is composed of two subunits: a smaller 30S subunit and a larger 50S subunit. These subunits work together to synthesize proteins by translating messenger RNA (mRNA) into amino acid sequences. In addition to prokaryotes, the 70S ribosome is also present in mitochondria and chloroplasts of eukaryotic cells, reflecting their evolutionary origins. The ribosome plays a crucial role in the process of translation, where it reads the mRNA and assembles the corresponding amino acids to form proteins essential for cellular functions.