Question

Trp Operon 5. The rate of transcription of the trp operon in E. coli is controlled by both repression and attenuation dr papde ia) Alternate secondary structures formed by the trpl tranecript Alternate 2 Regions 2 and 3 Atemate 1: Regions 1 and 2 basepared and regions 3 and 4 basepsired 54 140 Stop codon Transcribtion termination hairpin can NOT form a) Diagram and explain repression and attenuation regulatory mechanisms for the trp operon when tryptophan is present and absent. b) What likely effect would deletion of the trpL region of the trp operon have on trp E D-C-B-A in E. coli cells growing in the presence of tryptophan? c) You mutate the trpL sequence such that the two UGG Trp codons at positions 54-56 and 57-60 (refer to figure) in the mRNA leader sequence were changed to GGG Gly codons. What would most likely happen to trp operon regulation when tryptophan is present and absent? How would that differ when glycine is present and absent?

Answer 1

9 absenes of tryptophan trpR res car- > No Transcription continues Cinactve) n presence of eruptophan ( eTsso) n presen ce operom 3+ cuell Bleck ransempham Aehve then the aehive oomplex ove'll bind cpetator site to enhubit tonnscm、P Ham on.

for atenuatin- Ribosome strusture 2 as eodene for tmp ufr trp on 2 and 3 paure and thene to i no pauron 2 and y As a resuultno terminatm structe re
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b. trp L A #en uafor h-pl cs not there, then atten ua for U not present no attenuation So, tn presence trp also , there But "repression畊procerc cvet continue. Repressor Protein vetl get actve at hugh tbrp lavel cohuch elbmately leads to low tranc crtption . 94 thi trwo cedons are shanged to y (56G) codm, then tha operon evelt not be con trolled under trp level Nouo, e Gly e be present abund anty transemphm wet be stopped Trp well mot afect trancertphen mesent aburnd aunt