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RNAProtein160-page5 - do not code for specific amino acids...

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Gene Expression – DNA to Protein - 5 The DNA Code and How It is Used The information of DNA is coded into three-nucleotide-long sequences (a triplet code) along the length of the DNA molecule. Each triplet sequence is a "code word" for one specific amino acid. DNA molecules contain a linear sequence of triplets that specify which amino acids a protein will contain, and the sequence, or order, in which these amino acids will peptide bond to form a polypeptide. In addition to the triplet sequences, there are start and stop regions of the DNA associated with these instructions for protein synthesis, and regions within the DNA molecule that do not code and are removed by RNA processing after transcription. The DNA code is non-overlapping and there are no separators between the triplets. Although there can be 64 different DNA code words, (the number of combinations of three of the four different nucleotides) three of code words are "nonsense" and
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Unformatted text preview: do not code for specific amino acids. The three "nonsense" code words specify the end of a polypeptide coding. As stated in our preview, DNA is used to synthesize molecules of RNA by the process of transcription. A mRNA nucleotide triplet (synthesized from a DNA template) that codes for a specific amino acid is a complementary (rather than identical) codon to the DNA. Synthesis of RNA (transcription) follows the same nitrogen base pair rules that dictate DNA replication. Each mRNA transcript will be a faithful, but complement copy of the nucleotides of the DNA template. The codons for each of the amino acids are known, as well as specific codons that are used as start and stop messages. To determine which amino acids correspond to which nucleotide triplets, codon tables have been created....
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