2.10. Ribosomes

The ribosome is a complex molecule made of ribosomal RNA molecules and proteins that form a factory for protein synthesis in cells. In 1955, George E. Palade discovered ribosomes and described them as small particles in the cytoplasm that preferentially associated with the endoplasmic reticulum. Along with his colleagues, Palade discovered that ribosomes performed protein synthesis in cells, and he was awarded the Nobel Prize in 1974 for his work. Each ribosome is composed of a large and small subunit that together form a single unit composed of several ribosomal RNA molecules and dozens of proteins. The ribosome is responsible for translating encoded messages from messenger RNA molecules to synthesize proteins from amino acids. The ribosome translates each codon, or set of three nucleotides, of the mRNA template and matches it with the appropriate amino acid in a process called translation. The amino acid is provided by a transfer RNA (tRNA) molecule. Each newly translated amino acid is then added to the growing protein chain until the ribosome completes the process of protein synthesis.