A ribosome is a small, complex molecular machine found in all living cells. Its primary function is to synthesize proteins by translating messenger RNA (mRNA) into amino acid sequences. Ribosomes can be found floating freely in the cytoplasm or attached to the endoplasmic reticulum, forming what is known as the rough endoplasmic reticulum. Ribosomes are made up of ribosomal RNA (rRNA) and proteins, and they consist of two subunits: a large subunit and a small subunit. During protein synthesis, the ribosome reads the sequence of the mRNA and assembles the corresponding amino acids into a polypeptide chain, which eventually folds into a functional protein.