The
ribosome () is a complex
molecular machine found within all living cells, that serves as the site of
biological protein synthesis (translation). Ribosomes link
amino acids together in the order specified by
messenger RNA (mRNA) molecules. Ribosomes consist of two major components: the small ribosomal subunit, which reads the RNA, and the large subunit, which joins amino acids to form a
polypeptide chain. Each subunit is composed of one or more
ribosomal RNA (rRNA) molecules and a variety of
proteins. The ribosomes and associated molecules are also known as the
translational apparatus.