The central dogma of molecular biology states that the information encoded in DNA is transferred to RNA, which then directs the synthesis of proteins based on these instructions. First, during transcription, DNA is used as a template to synthesize messenger RNA or mRNA. The mRNA represents a copy of the coding strand of DNA, except that the thymines are replaced with uracils. Next, the mRNA is translated into a chain of amino acids by a ribosome. Here, groups of three nucleotides on mRNA, also known as codons, bind to complementary sequences or anticodons on the transfer RNA or tRNA molecules. Each tRNA is attached to a particular amino acid, depending on the specific codon. For example, the codon CCA binds to a tRNA attached to proline, while AGC binds to a tRNA attached to serine. In this way, the genetic code specifies the order of amino acids in the resulting polypeptide, which is further processed to become a functional protein.