Exam 8: Control of Gene Expression

Which of the following statements about nucleosomes is TRUE?

Which of the following is NOT involved in post-transcriptional control?

In principle, how many different cell types can an organism having four different types of transcription regulators and thousands of genes create?

You are interested in the regulation of gene Q.Proteins G, H, and J are proteins that are important for regulating gene Q, and bind to its promoter region in a sequence-specific fashion.Proteins G and H both bind to site "A" but cannot bind to site "A" at the same time.Protein J binds to site "B" on the promoter.The promoter region is diagrammed in Figure 8-20. Figure 8-20 You develop a cell-free transcriptional system to study the effects of proteins G, H, and J on the transcription of gene Q.Using this system, you can examine the effects of adding these proteins to the transcriptional system in equal amounts and measuring how much gene Q is produced.When you add these proteins to the system, you get the results shown in Table 8-20. $\text { experiment }$$\text { reaulator protein added }$$\text { Q mRNA }$ number G H J made? 1 - - - no 2 + - - no 3 - + - yes 4 - - + yes 5 + + - no 6 + - + yes 7 - + + yes 8 + + + yes Table 8-20 Your colleague looks at your data above and predicts that protein G will bind more strongly to the DNA at site A, compared to protein H.Which experiment above is critical for this prediction?

The gene for a hormone necessary for insect development contains binding sites for three transcription regulators called A, B, and C. Because the binding sites for A and B overlap, A and B cannot bind simultaneously. You make mutations in the binding sites for each of the proteins and measure hormone production in cells that contain equal amounts of the A, B, and C proteins. Figure 8-52 summarizes your results. In each of the following sentences, fill in the blank one of the phrases within square brackets to make the statement consistent with the results. -Protein A binds to its DNA binding site __________ [more tightly/less tightly] than protein B binds to its DNA binding site.

Which of the following statements about miRNAs is FALSE?

You are interested in examining the Psf gene.It is known that Psf is normally produced when cells are exposed to high levels of both calcium (Ca²⁺) and magnesium (Mg²⁺).MetA, MetB, and MetC are important for binding to the promoter of the Psf gene and are involved in regulating its transcription.MetA binds to the "A" site in the promoter region, MetB to the "B" site, and MetC to the "C" site.You create binding-site mutations in the A, B, and C sites and observe what happens to transcription of the Psf gene.Your results are summarized in Table 8-12. $\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\underline{\text { Transcription in the presence of } \mathrm{Ca}^{2+} \text { and/or } \mathrm{Mg}^{2+}}$ Binding sites present No or With With With and A, B, and C - - - ++ none - - - - A only - - + + B only - - - - C only - + - + A and B only - - - + A and C only - + + ++ B and C only - - - + $\text {For this table: -= no transcription of Pst,}$ $\text { += low level of transcription of Psf, and}$ $\text { ++= high levels of transcription of Pst.}$ Table 8-12 Which of the following proteins are likely to act as gene repressors?

Which of the following is not a good example of a housekeeping protein?