BIOL 2020 Lecture Notes - Lecture 15: Phosphatase, Digestion, Methyl Group
29 Apr 2016
School
Department
Course
Professor
Document Summary
Shine-dalgarno sequence (uaaggaggu) is situated ~8 bp upstream of the start. Small ribosome subunit binds this sequence and is situated appropriately at the start. Negative translational control (ex. the translation of a polycistronic mrna is repressed by one of its products) *don"t need to memorize consensus sequences of different proteins. The ribosome binds the bap at the 5" end of the mrna and scans (5" to 3") for an appropriate start aug. The start aug is often found within the kozak consensus sequence: gccrccaugg. When the ribosome encounters this sequence, it initiates translation. More codons than trnas which indicates that some trnas recognize more than one codon: the wobble hypothesis explains why cells usually have fewer trnas than expected. Codon-anticodon base pairings are antiparallel. but the base sequences are always written in the 5" to 3" direction: ex. Mrna codon 5"-agg-3" base pairs with trna anticodon 3"-ucc-5". Since base sequence is always in 5"-3" direction; the trna anticodon is 5"-ccu-3".
