Translation is decoding mRNA to build a polypeptide (chain of amino acids). In an mRNA, the instructions for building a polypeptide come in groups of three nucleotides called codons. These relationships between mRNA codons and amino acids are known as the genetic code. Initiation is when the ribosome gets together with the mRNA and the first tRNA so translation can begin. Elongation is when amino acids are brought to the ribosome by tRNAs and linked together to form a chain. Termination is the finished polypeptide is released to go and do its job in the cell.