Coli glucose glucose breakdown enzymes present ecoli

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: te fuel sources E.coli + glucose = glucose breakdown enzymes present ) E.coli + glucose & lactose = only glucose breakdown enzymes present ) If lactose induces ( derepresses ) the operon…. Why does lactose + glucose = no induction? Lac operon is under “+” control by CRP gene cAMP activates CRP CRP gene is “inactive” until bound by cAMP cAMP CRP CRP inactive active Glucose represses the Lac operon ATP cAMP Adenyl cyclase (-) glucose CRP gene is “inactive” until bound by cAMP glucose cAMP CRP CRP inactive active Summary lactose inactivates the repressor glucose inactivates adenyl cyclase For z,y,a, transcription, there must be active CRP product AND repressor inactivation. Are there examples of “repressible” operons? The Tryptophan Operon Tryptophan is a non-essential amino acid in E.coli Experiments Ecoli + tryptophan = No trp synthetic enzymes E.coli & no trp = trp synthetic enzyme production Conclusion?? Trp genes on until trp is added Trp regulator codes for “inactive” repressor Trp acts like a “corepressor” to active repressor corepressor See Bio 7 for “attenuation” of trp operon See Bio 7 for “attenuation” Cis/Trans regulation studies …see Bio 97 The remainder of this chapter is covered in detail in Bio 8...
View Full Document

This note was uploaded on 12/27/2012 for the course BIO 93 taught by Professor Rodriguez during the Fall '12 term at Irvine Valley College.

Ask a homework question - tutors are online