What is the main function of ribosomes in cells?

Ribosomes play a crucial role in cells primarily for protein synthesis, which is the correct answer. They facilitate the translation process, where messenger RNA (mRNA) is interpreted to assemble amino acids into polypeptide chains, forming proteins. This process occurs in two main stages: initiation, where the ribosome assembles around the mRNA, and elongation, where the ribosome moves along the mRNA and adds corresponding amino acids to the growing polypeptide chain.

Ribosomes can be found either floating freely in the cytoplasm or attached to the endoplasmic reticulum, contributing to either free or membrane-bound protein synthesis. The proteins synthesized are vital for numerous cellular functions, ranging from structural roles to enzymatic activity. This is why ribosomes are considered the site of protein synthesis in all living cells, highlighting their essential function in the overall machinery of cellular life.