An exception to the Knudsen \"two-hit\"- hypothesis is dominant-negative mutatio

Question

An exception to the Knudsen "two-hit"- hypothesis is dominant-negative mutations in the p53 gene. amplification of the c-Myc gene. often observed in familial retinoblastoma. mutations giving rise to non-functional tumor suppressor proteins. Human Papilloma Virus (HPV). Assume that E. coli is growing in a minimal medium containing neither glucose nor lactose. Which of the following mutations affecting the lac operon regulatory region would result in the highest rate of transcription initiation? -10 region mutation changing TATGTT to TACGTT deletion of the CRP response element deletion of the lacl gene overexpression of the lacl gene deletion of the gene encoding the CRP protein

Explanation / Answer

7 Q ANS C ) Deletion of lacI gene result in highest rate of transcription intiation .Laci acts as repressor molecule it control the expression of lac Z,Y,A, genes ,when deletion of the lacI gene ,lac repressor would not be avaliable so not able to bind to promoter . RNA polymerase is continously binds to promoter and keep on express the transcription rate .

a) Mutations in promoter region shows loss of consensus sequence and these mutation interfere with transcription intiation

b) When gulcose is absent ,cAMP receptor protein (CRP) binded to promoter and expresses lacopern transcription

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