Exam 15: Regulation of Gene Expression

Attenuation is known to occur in the lac operon.

What is the function of RNA interference?

What type of genetic control,positive or negative,typically results when transcription factors interact with DNA?

The enzyme permease cleaves the linkage between glucose and galactose residues in lactose.

Regarding eukaryotic and prokaryotic genetic regulation,what process seems to be the most similar between the two?

(a)Describe by labeled diagram the structural components of the lac operon in E.coli. (b)State the function of the lac regulator gene. (c)State the function of $\beta$ -galactosidase in the lac system. (d)Show by diagram the manner in which lactose brings about transcription of the three structural genes of the lac operon. (e)Explain why certain mutations in the regulator gene (I^-)of the lac system result in maximal synthesis of $\beta$ -galactosidase,permease,and transacetylase even in the absence of the inducer (lactose).

Mutations in the lacI and lacO genes of the lac regulatory system in E.coli often lead to full transcription of the three structural genes,even when no lactose is available to the organism.Such mutations would be called ________.

In the diagram below,what type of control,positive or negative,is operating?

A constitutive mutation in the lac operon may be of several types.Name two types of constitutive mutations.