Exam 19: Control of Gene Expression in Eukaryotes

Imagine that you are studying the control of fi- globin gene expression in immature red blood cells mature red blood cells contain fi- globin protein, but lack a nucleus and, therefore, the fi- globin gene). If you deleted a sequence of DNA outside the protein- coding region of the fi- globin gene and found that this increased the rate of transcription, the deleted sequence likely functions as an)

Figure 19.1 -Predict what would occur in the experiment shown in Figure 19.1 if Tonegawa and colleagues had mistakenly inserted the antibody gene enhancer in reverse orientation backward) into the fi- globin gene.

Figure 19.1 -In the experiment shown in the figure above, Tonegawa and his colleagues were able to express fi- globin in an antibody- producing cell that normally does not express fi- globin. They achieved this result by splicing an enhancer from an antibody- producing gene into the protein- coding portion of the fi- globin gene. They then introduced this recombinant gene into cultured antibody- producing cells. Why was the choice of Antibody- producing cells-rather than, say, muscle or skin cells-critical for the success of this experiment?

Imagine you've isolated a yeast mutant that contains histones resistant to acetylation. What phenotype do you predict for this mutant?

Regulatory transcription factors

In colorectal cancer, several genes must be mutated for a cell to develop into a cancer cell. Which of the following kinds of genes would you expect to be mutated?

One way to detect alternative splicing of transcripts from a given gene is to

If a cell were unable to produce histone proteins, which of the following would be a likely effect?

The rate of translation can be slowed drastically when a ribosomal protein is phosphorylated in response to a sudden temperature increase or viral infection. In this case, the phosphorylated ribosomal protein is under Control, and the phosphorylation of this ribosomal protein leads to widespread control.

Histone acetyl transferases exert their effect on gene activity by

The TATA- binding protein TBP) binds to

Which method is utilized by eukaryotes to control their gene expression that is not used in bacteria?

In the roundworm C. elegans, the lin- 4 gene produces an RNA that forms a hairpin structure. One of the strands in the double- stranded region of lin- 4 hairpin RNA is complementary to the mRNA of a protein- coding gene, lin- 14. Predict the effect of expressing lin- 4 RNA during development.

An example of a basal transcription factor is

What is a key property of DNase that makes it useful for assessing whether chromatin is in a closed tightly condensed) or open loosely packed) configuration?

Use the following information when answering the corresponding questions). A group of enzymes known as cytosine- specific DNA methylases recognize CpG dinucleotide sequences-that is, a cytosine followed by a guanosine G) in one DNA strand-and add methyl groups to the cytosine. Many proteins bind to methylated CpG, including the methyl- CpG binding protein 2 MeCP2). MeCP2 binding leads to the formation of a closed state of chromatin, thus silencing gene expression. A recent paper by Chen et al. reported an interesting mechanism of regulating transcription of a gene via MeCP2 W. Chen, Q. Chang, Y. Lin, A. Meissner, A. E. West, E. C. Griffith, R. Jaenish, and M. Greenberg. 2004. Derepression of BDNF transcription involves calcium- dependent phosphorylation of MeCP2, Science 302:885-89). This gene, called BDNF, encodes brain- derived neurotrophic factor BDNF)-a protein that plays an important role in nerve cell and central nervous system function, including memory and learning. Remarkably, most cases of Rett syndrome, an important cause of mental retardation in females, are due to loss- of- function mutations of MeCP2. -Elsewhere in the paper, Chen et al. state that "BDNF is encoded by a complex gene with four well- characterized promoters that give rise to at least eight different mRNAs." What mechanism could account for the production of these different BDNF mRNAs?

Which of the following is most critical for the association between histones and DNA?

p53 activates genes that

Ovalbumin, the major protein of egg white, is secreted by cells that line the oviduct as the bird egg moves down the oviduct. Imagine you're repeating the classic Weintraub- Groudine experiment, but with a twist: You're assaying the DNase sensitivity of the promoter regions of the fi- globin and ovalbumin genes in oviduct cells of laying hens. In this case you expect to find that

Twenty- five years ago, when Oshima and colleagues discovered that a mutation in the GAL4 gene led to the inability to synthesize all five enzymes required for galactose catabolism breakdown), they couldn't be blamed for wanting to apply a bacterial model to explain this finding. What they expected, but did not find, was