Exam 19: Control of Gene Expression in Eukaryotes

Not long ago, it was believed that a count of the number of protein- coding genes would provide a count of the number of proteins produced in any given eukaryotic species. This is incorrect, largely due to the discovery of widespread

Which of the following types of mutation would convert a proto- oncogene into an oncogene?

If the DNA sequences of a particular gene in a skin cell and a liver cell were compared, there would be

The reason for differences in the sets of proteins expressed in a nerve and a pancreatic cell of the same individual is that nerve and pancreatic cells contain different

Which of the following best explains the function of proto- oncogenes in eukaryotic cells?

Imagine you've isolated a yeast mutant that contains a constitutively constantly) active histone deacetylase. What phenotype do you predict for this mutant?

Which of the following is FALSE?

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. -A patient is undergoing genetic screening for cancer. The results show the patient has many proto- oncogenes. Based on this information only, which of the following statements is correct regarding the probability that this patient will develop cancer in the very near future?

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

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

The normal function of a tumor suppressor gene is to

Which of the following allows more than one type of protein to be produced from one gene?

Why can gene expression be altered more easily at the level of post- transcriptional processing in eukaryotes than in prokaryotes? Because

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. -A scientist has a vial containing DNA and tries to digest it with DNA digesting enzymes. After analyzing it, she finds that no digestion occurred. What would be the most likely reason for this?

If DNA were inflexible, which of the following would not function?

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. -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

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

Alternative splicing takes place in the

How do chromatin- remodeling complexes recognize the genes they should act on?

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