BCHM 4116 1st Edition Lecture 30 Outline of Last Lecture 1 Protein Synthesis 2 Genetic Code Outline of Current Lecture 1 Rules in Condon Anticodon Pairing 2 Ribosomes 3 Translation Current Lecture Chapter 30 Protein Synthesis 1 30 3 Rules in Condon Anticodon Pairing a Third base of codon referred as the wobble position i A certain amount of wobble might be allowed in base pairing at this position ii Wobble rule 1 The 1st base anticodon U could recognize either an A or G in the codon 3rd base position 2 1st base anticodon G might recognize either U or C in 3 rd base position of codon 3 1st base anticodon I might interact w U C or A in codon 3 rd position 2 30 4 Ribosomes a Compact ribomucleoprotein particles found in cytosol of all cells as well as in matrix of mitochondria stroma of chloroplast b Mechanochemical systems that move along mRNA templats orchestrating the interactions b w successive codons corresponding anticodon presented by aminoacyltRNAs c catalyze formation of peptide bonds b w growing peptide chain d Prokaryotic Ribosomes 30S and 50S subunits i 30S smaller subunit 1 21 diff protein and 1 rRNA 16S rRNA ii 50 S larger subunit 1 31 diff proteins 2 rRNA 23SrRNA 5SrRNA e prokaryotic ribosomes are made from 50 diff proteins 3 diff RNAs i Ribosomal proteins serve a large structural role in ribosomes 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 Primary function is to brace and stabilize the rRNA conformations w in ribosomal subunits ii rRNA acts as scaffold upon which various ribosomal proteins convene f Ribosomes spontaneously self assemble in vitro i Under appropriate conditions of pH ionic strength spontaneous self assembly into functionally competent subunits take place g Eukaryote Ribosomes i Eukaryotic cytosolic ribosomes are larger more complex ii But still retain core sturcutral functional properties as prokaryotes 3 30 5 Translation a Requires GTP specific protein factors b Initiation i Binding of mRNA by small ribosomal subunit ii Followed by initatior aminoacyl tRNA that recognizes 1 st codon iii Large ribosomal subunit then joins initiation complex c Initiator tRNA i tRNAfMET is a particular tRNA for reading an AUG codon that signals the start site d Shine Dalgarno sequence i 16s rRNA of 30S ribosomal subunit recognize translation initiation seq ii Shine Dalgarno seq ribosome binding site 1 Purine rich mRNA sequence e Initiation Factors i Soluble proteins required for assembly of proper initiation complex ii IF 1 1 Binds 30S A site 2 Prevents tRNA binding iii IF 2 1 G protein that binds fMet tRNAfMet 2 Interacts w IF 1 iv IF 3 1 Binds 30S E site 2 Prevents 50S binding 3 Essential for mRNA binding by 30S subunit 4 MUST leave b4 50S subunit can join v Initiation complex 1 30S subunit gives 30S initiation complex 2 50S subunit adds in to form 70S initiation complex