CH_8_student_outline

87 ambiguities resolved by nirenberg and philip leder

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Unformatted text preview: trinucleotide mRNAs of known sequence to tRNAs charged with radioactive amino acid with ribosomes Fig. 8.8 5' to 3' direction of mRNA corresponds to N-terminal-to-Cterminal direction of polypeptide. One strand of DNA is a template. The other is an RNA-like strand (non-template strand). Nonsense codons cause termination of a polypeptide chain UAA (ocher), UAG (amber), and UGA (opal). Fig. 8.9 Codon consist of a triplet codon each of which specifies an amino acid. Summary Code shows a 5' to 3' direction. Codons are non-overlapping. Code includes three stop codons, UAA, UAG, and UGA that terminate translation. Code is degenerate. Fixed starting point establishes a reading frame. AUG in an initiation codon which specifies reading frame. 5'- 3' direction of mRNA corresponds with N-terminus to Cterminus of polypeptide. Mutation modify message encoded in sequence Frameshift mutations change reading frame. Missense mutations change codon of amino acid to another amino acid. Nonsense mutations change a codon for an amino acid to a stop codon. Do living cells construct polypeptides according to same rules as in vitro experiments? Studies of how mutations affect amino-acid composition of polypeptides encoded by a gene Missense...
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This note was uploaded on 08/04/2009 for the course BIOL 2153 taught by Professor Larkin during the Fall '03 term at LSU.

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