BIOL 2321 Lecture Notes - Lecture 25: Phosphorylase, Ribonucleotide, Aminoacyl-Trna
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Unformylated met: degeneracy minimizes the deleterious effect of mutations (3. If the code were non-degenerate, 44 codons would be nonsense and act as chain terminators during protein synthesis. Chain termination mutations usually lead to inactive (or no) protein. Many mutations are effectively silent, because the substitution yields a codon specifying the same amino acid: discovery of termination codons poly(gua) = only two homopolypeptides no incorporation of any amino acid with. Uag poly(gau) = only two homopolypeptides no incorporation of any amino acid with. Uga poly(guaa) = tripeptides only poly(auag) = tripeptides only. Uag, uga and uaa are nonsense codons and do not specify an amino acid = termination codons: each amino acid is specified by a group of three nucleotides (codon) in messenger. Rna: genetic code is non-overlapping, the sequence of nucleotides is read sequentially from a fixed starting point =