Biochemistry 2280A Lecture Notes - Lecture 25: Aminoacyl-Trna, Missense Mutation, Nonsense Mutation
4 Apr 2016
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Spells out the aa sequence in 3 leter words called codons. A lot of hidden info in geneic code. Cell needs 20 dif codons (21 if you include stop codon) Since any nucleoide can be a, u, g, c, there are 64 dif 3 base codons. Key features of the geneic code: universal; all organisms use the same geneic code. The code has evolved once: nonoverlapping. Problem with overlapping code is that each posiion will decide what the next posiion will have to be; restricions on what aa residue would follow e/o. Nonoverlapping means you can it any aa beside e/o; no restricions: no gaps (commaless); directly coninuous, all listed together. If there was a gap between every codon, that would take up extra space would serve no funcion. No gaps means minimizing size of genome: redundancy: some codons specify the same amino acid. 61 codons for 20 aa (minus stop codon)
