BIO206H5 Lecture Notes - Lecture 8: Lac Operon, Recognition Sequence, Repressor
Document Summary
Will bind to operator (o1) and then can also bind with o2/ o3 not all both at the same time (e. g o1and o2 ) and (o1and o3) Recognition sequence binds to the major group. Lactose acts allosterically, resulting in change in the 3-d shape (conformation ) of the repressor tetramer. - helix -turn-helix motifs are no longer in the correct spatial orientation to interact with operator this - causes the repressor to the release the operator. Positive regulation - some forms of transcription regulation act to improve the e ciently by improving the act of rna polymerase. Cap (activator) on its on cant do anything need camp (inducer ) to bind to cap site. Cap + camp improving the way polymerase works. Cap without camp it is bound loosely and doesn"t work probably or as e ciently. Glucose increase = camp down = lacz mrna decrease. Glucose decrease = camp high = lacz mrna increase.
