BIOL 2100 Lecture Notes - Lecture 37: Hbb, Radiography, Filter Paper
19 Nov 2016
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The cap and cap binding site are responsible for positive control. The repressor and operon are responsible for negative control. Glucose is low when cap bonds, which has cyclic amp because the glucose is not there to inhibit. Lactose is low because the repressor is bound, usually the lactose present acts as an inducer and allows transcription to occur. Repressor not bound, but cap is bound low glucose, high lactose. Not as efficient, making things not needed. Genes would be expressed, when not needed to be expressed. Expression would turn on when there is low glucose and no lactose. If only positive control existed no repressors or operators. Arabinose causes change in shape, different conformation enhances transcription (rna. In absence of arabinose , blocks transcription polymerase able to associate with promoter) Example of positive and negative control because same protein can act as both in different conformations. Plasmid contained gene to encode for arac.
