BCHM 4116 1st Edition Lecture 30Outline of Last Lecture 1. Protein Synthesis 2. Genetic Code Outline of Current Lecture 1. Rules in Condon-Anticodon Pairing2. Ribosomes 3. Translation Current LectureChapter 30: Protein Synthesis 1. 30.3 – Rules in Condon-Anticodon Pairinga. Third base of codon referred as the wobble position i. A certain amount of wobble might be allowed in base pairing at this positionii. Wobble rule: 1. The 1st – base anticodon U could recognize either an A or G in the codon 3rd-base position2. 1st base anticodon G might recognize either U or C in 3rd base position of codon3. 1st base anticodon I might interact w/ U, C, or A in codon 3rd position 2. 30.4 – Ribosomesa. Compact ribomucleoprotein particles found in cytosol of all cells, as well as in matrix of mitochondria & stroma of chloroplastb. Mechanochemical systems that move along mRNA templats, orchestrating the interactions b/w successive codons & corresponding anticodon presented by aminoacyl-tRNAsc. & catalyze formation of peptide bonds b/w growing peptide chain d. Prokaryotic Ribosomes = 30S and 50S subunits i. 30S – smaller subunit1. 21 diff. protein and 1 rRNA (16S rRNA) ii. 50 S – larger subunit1. 31 diff. proteins & 2 rRNA (23SrRNA & 5SrRNA)e. prokaryotic ribosomes are made from 50 diff. proteins & 3 diff. RNAsi. Ribosomal proteins serve a large structural role in ribosomesThese 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 vitroi. Under appropriate conditions of pH & ionic strength, spontaneous self-assemblyinto functionally competent subunits take place g. Eukaryote Ribosomesi. Eukaryotic cytosolic ribosomes are larger & more complexii. But still retain “core” sturcutral & functional properties as prokaryotes3. 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 1st codon iii. Large ribosomal subunit then joins initiation complex c. Initiator tRNAi. tRNAfMET is a particular tRNA for reading an AUG codon that signals the start sited. Shine-Dalgarno sequencei. 16s rRNA of 30S ribosomal subunit recognize translation initiation seq. ii. Shine – Dalgarno seq. = ribosome binding site1. Purine rich mRNA sequencee. Initiation Factorsi. Soluble proteins required for assembly of proper initiation complexii. IF – 1 1. Binds 30S A site 2. Prevents tRNA bindingiii. IF – 21. G- protein that binds fMet-tRNAfMet2. Interacts w/ IF -1iv. IF – 31. Binds 30S E site2. Prevents 50S binding 3. Essential for mRNA binding by 30S subunit 4. MUST leave b4 50S subunit can joinv. Initiation complex1. 30S subunit gives 30S initiation complex 2. 50S subunit adds in to form 70S initiation