step in this process is called TRANSCRIPTION where a coding region of DNA is converted to messenger RNA mRNA During transcription mRNA is made from the DNA sequence following the base pair rule except RNA does not contain the base Thymine but instead has Uracil The mRNA then leaves the nucleus and goes to a ribosome in the cell s cytoplasm The ribosome reads the message three bases at a time called a CODON Each codon will specify a single amino acid The amino acids are joined together and folded into a protein a process called TRANSLATION Key Points DNA is used to make a copy of mRNA transcription mRNA leaves the nucleus and goes to ribosomes 3 bases codon 1 codon a single amino acid A chain of amino acids a protein Protein synthesis is also called translation Biologists use a codon chart or a codon wheel to determine the amino acids Amino acids are usually abbreviated on these charts as three letter words like Cys and Ser First base in codon U C G UUU UUC UUA UUG CUU CUC CUA CUG AUU UCU UCC UCA UCG CCU CCC CCA CCG ACU AUC lle ACC AUA ACA AUG ACG GUU GCU GUC GCC GUA GCA GUG GCG Phe Leu Leu Met of start Second base in codon C A Val Ser Pro Thr Ala UAU U UAC Tyr C UAA Stop UGA Stop A UAG Stop UGG Trp G CGU CAU CAC CAA CAG AAU AAC AAA AAG GAU GAC GAA GAG His Gin Asn Lys UGU UGC Asp Glu Cys 3 CGC CGA CGG AGU AGC AGA AGG Arg GGU GGC GGA GGG Arg Ser Gly C GUCAG U A G Third base in codon Val Ala Ser G 10 G Arg A Lys Asp A 24 OP GU Asn A Cu Glu UC U C G Gly Phe Leu UA U G C G C Thr GA A A Met Start CU C GU GU A C UG 110 2 PO UA GACGC C 2 A Arg C A A A G C Ser G 2 U 15 UC Gin 2109342 Tyr His PG SONA C So UC G Stop Stop G Trp Stop Cys Pro Leu