BIOB 375 1st Edition Lecture 9 Outline of Last Lecture I. RNAa. mRNA, rRNA, tRNA II. Message RNA processinga.5’ cap, 3’ poly-A tail, RNA splicingOutline of Current Lecture III. rRNAa. processing IV. TranslationCurrent Lecture- mRNA processing only occurs in Eukaryotic cellsrRNA Processing (occurs in both Prokaryotic and Eukaryotic cells) - Methylation- CleavageIn Prokaryotic rRNA- Precursor rRNA transcript (30S)- Ribosome 70SIn Eukaryotic rRNA- Precursor rRNA transcript (45S)- Ribosome 80S-rRNA and tRNA isn’t translated, but mRNA isTranslation- Always starts from “AUG” after the Shine-Dalgarno sequence “UAAGGAGGU”- The stop codon is “UAG” or “UGA” or “UAA”- Once there is a stop codon, the translation will stop- The region between the start codon and stop codon is the coding region- From 5’ to start codon is a region called 5’ untranslated region- From stop codon to 3’ is a region called the 3’ untranslated region- Basic structure of protein is the amino acid- There are a total of 64 codons, 3 stop codons, 61 encode amino acids – called sense codons- Two amino acids are encoded by single codon- Degeneracy: more than one codon can be coded for the same amino acid- The codon moves every three and won’t overlap- The Wobble position is located at the 3’ end, it is called with because of the improper pairProcess:- Find the first start codon AUG Met- Then move toward the 3’ end, every 3 nucleotides for one amino acid, no overlap- Stop at stop codon, then look back to name the amino acid sequence (do not include stop codon or the cap)- UTR = untranslated region- The 3’ UTR does not include the Poly-A
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