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 structure and function of the 70S ribosome are crucial for cellular processes, making it a key target for certain antibiotics that inhibit protein synthesis.