Ribosomes are molecular machines found within all cells. They perform protein synthesis, translating instruction-sequences carried by mRNA
strands into proteins. The instructions carried by the mRNA
strands have been read from the cell's DNA strand by other molecular machines, in a process known as transcription
With the help of tRNA
molecules, ribosomes link amino acids
together in the order specified by the codons of messenger RNA (mRNA
) molecules. When strung together in the specified order, the amino acids
form polypeptide chains (unfolded protein molecules). These, in turn form all biological components, including the molecular machines found within cells.
Ribosomes consist of two major components: the small and large ribosomal subunits. These come together when needed to convert mRNA
instruction strands into unfolded proteins.
Ribosomes and their associated molecules are sometimes referred to as the translational apparatus.