Exam 18: Control of Gene Expression in Eukaryotes

Alternative splicing takes place in the

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 question(s). A group of enzymes known as cytosine-specific DNA methylases recognize CpG dinucleotide sequences-that is, a cytosine (C)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. -The authors state,"In this study,we report that,in the absence of neuronal activity,MeCP2 binds specifically to BDNF promoter III and functions as a negative regulator of BDNF expression.In response to neuronal activity-dependent calcium influx into neurons,MeCP2 becomes phosphorylated and is released from the BDNF promoter,thereby permitting BDNF promoter III-dependent transcription." Reading this statement in isolation,it would be easy to have the impression that MeCP2 works as a negatively acting transcription factor.However,based on the summary of the paper provided above,MeCP2 acts as a

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 β-globin and ovalbumin genes in oviduct cells of laying hens.In this case you expect to find that

p53 activates genes that

The TATA-binding protein (TBP)binds to

A pattern of inheritance in which heritable differences in phenotype are due to something other than differences in DNA sequence is

A gene is a

Histone acetyl transferases exert their effect on gene activity by

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

The normal function of a tumor suppressor gene is to

Regulatory transcription factors

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?

An example of a basal transcription factor is

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

The primary difference between an enhancer and a promoter-proximal element is that

Gene expression is often assayed by measuring the level of mRNA produced from a gene.If one is interested in knowing the amount of a final active gene product,a potential problem of this method is that it ignores the possibility of

The association of DNA with nucleosomes means that the default state for eukaryotic genes is to be

An important way to regulate the stability of mRNA is through

Figure 18.1 -Predict what would occur in the experiment shown in Figure 18.1 if Tonegawa and colleagues had mistakenly inserted the antibody gene enhancer in reverse orientation (backward)into the β-globin gene.