2021/2/21 Topic 1: mRNA a Only a portion of each mRNA can be translated a The protein-coding region of the mrna consists of an ordered series of 3 -nt-long units called codons that specify the order of amino acids 102021/2/21 10 Topic 1: mRNA ◼ Only a portion of each mRNA can be translated. ◼ The protein-coding region of the mRNA consists of an ordered series of 3-nt-long units called codons that specify the order of amino acids