Regulation

1) Describe how the lac operon is regulated when glucose is absent but lactose is present. Include reference to c-AMP, Catabolic Activating Protein, the operator, RNA polymerase, and the repressor protein.

2) The trp operon is a bit more complicated. First, describe how it is a repressible system invovling the effects of trp on a repressor protein.

3). Second, explain how the presence or absence of trp influence translation, through the formation of loops in the m-RNA, and the progression of transcription.

4) As you might suspect, energetically efficient regulation of gene activity is under strong selection. In other words, organisms that waste energy making proteins they don't need have less energy to spend on reproductive success and are at a selective disadvantage. Explain the energetic efficiency of the lac operon in this context, explaining why the operon is only ON when glucose concentrations are LOW and lactose cocnentrations are HIGH. Address both effects (why it is adaptive to be off if glucose is high and adaptive to be off is lactose is low).

5) From a regulatory standpoint, why should we expect gene regulation to be more complicated in multicellular eukaryotes than in prokaryotes? (The bold-face is a hint... : ) )

6) What is chromatin remodeling and how can that affect gene activity?

7) How does methylation typically affect gene activity?

8) What do multiple site for transcription proteins allow for, in terms of gene regulation?

9) What are transcription factors? What is the latest explanation for the evolution of Cys2-His2 zinc finger tranacription factors?

10) The split-gene structure of eukaryotes allows for an additon "step" of genetic regulation.... the transcript processing stage. Describe what happens to the CT/CGRP gene in thyroid and nerve cells.

11) What are siRNA's and miRNA's, and how can they influence m-RNA processing and gene expression?