Central dogma of genetics.
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   Sequences  of DNA called genes serve as templates for transcription of
   messenger  RNA  (mRNA),  following the base-pairing rules - remember A
   pairs with U in RNA.
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   During  translation,  sequences  of base triplets (codons) in the mRNA
   specify amino acids that make up a protein (polypeptide) chain.
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   The  process of transcription and translation results in expression of
   the gene.