BCHM 4116 1st Edition Lecture 29Outline of Last Lecture 1. Eukaryotic Transcripts Processed and Delivered to Ribosome for TranslationOutline of Current Lecture 1. Protein Synthesis 2. Genetic Code Current LectureChapter 30: Protein Synthesis 1. 30.1 – Genetic Codea. Triplet code – group of 3 bases codes for 1 amino acidb. Not overlappingc. If reading frame is displace by 1 base = shifted throughout d. Condon represent triplets of bases in mRNAi. Degenerate – each AA can be coded by any of several triplets ii. Meaning - 3 nonsense codons – UAA, UAG, UGA1. serve as termination codons – “Stop” signals indicating end of protein iii. Unambiguous – each 61 “sense” codons encodes only 1 AAiv. Codons representing the same AA or chemically similar AA tend to be similar in sequence1. Third-base degeneracy : often 3rd base in codon is irrelevant v. Universal 1. Conformity means that all extant organisms use same genetic code strong evidence that they all evolved from a common primordial ancestor 2. 30.2 – AA matched with proper tRNAa. Appropriate tRNAs have anticodons that can base-pair w/ codons specifying particular AAb. Aminoacyl-tRNA synthetase – catalyzes ATP dependent attachment of its specific AA to the 3’ end of its cognate tRNA molecule c. Aminoacyl-tRNA synthetase serves 2 purposes:i. Activates AA so that it will readily react to form a peptide bondii. Bridges the info. gap b/w AA and codonsd. 2 distinct classes of aminoacyl-tRNA synthetasesi. Class 1: adds AA to 2’-OH of terminal adenylate residue of tRNA before shifting itto 3’ – OH These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. Bind tRNA acceptor stem helix from minor groove sideii. Class 2: adds directly to 3’ – OH 1. Binds tRNA acceptor stem helix from major groove side e. Anticodon stem interacts w/ mRNA
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