Chapter 16: Gene Regulation in Eukaryotes II: Epigenetics Practice Questions

If a cell is fused with another cell, which of the following would be the best example of a trans-mechanism of epigenetic control? Multiple Choice A gene that is originally silenced in one cell but expressed in the other is silenced in the hybrid A gene that is originally silenced in one cell but expressed in the other is still expressed in the hybrid. The methylation pattern of the same gene from either cell is not altered There are no examples that could conform to a trans-mechanism

A gene that is originally silenced in one cell but expressed in the other is silenced in the hybrid

Epigenetic inheritance may occur at which of the following stages? Multiple Choice Oogenesis Spermatogenesis Embryogenesis All of the answers are correct

All of the answers are correct

Which of the following are molecular mechanisms used in epigenetic gene regulation? Multiple Choice DNA methylation Covalent histone modification Chromatin remodeling Answers A, B, and C are correct

Answers A, B, and C are correct

Feeding a specific diet to female mice may result in an increased proportion of pseudoagouti offspring if Multiple Choice The female carries the A^(vy) allele The offspring have the genotype A^(vy)a The transposon at the A^(vy) locus in the progeny is hypermethylated Answers B and C are correct

Answers B and C are correct

Which of the following is part of the mechanism for epigenetic regulation of the Igf-2 gene Multiple Choice Methylation of the H19 locus Methylation of the ICR and DMR domains Binding of CTC factors to methylated sequences Answers B and C are correct Answers A and C are correct

Answers B and C are correct

Which of the following is part of the process of X chromosome inactivation Multiple Choice Expression of Xist from both chromosomes at the start of the process Binding of multiple Xist transcripts to Xic on the X chromosome that will be inactivated Compaction of the active X chromosome into a Barr body Binding of Tsix transcripts to the X chromosome to be inactivated after the Xist transcripts binds to Xic

Binding of multiple Xist transcripts to Xic on the X chromosome that will be inactivated

What gene(s) is/are encoded in the Xic? Multiple Choice Xce Xist Tsix Both the Tsix and Xist are genes are in the Xic region

Both the Tsix and Xist are genes are in the Xic region

In cancer cells one allele of the tumor suppressor gene p53 is frequently mutated so that the protein is inactive, not produced, or deleted. The other allele will usually have a normal sequence and the promoter remains intact but the gene is not expressed. Sequencing with sodium bisulfite modification of DNA can be used to detect which cytosines are methylated. If the cancer cell DNA is sequenced what would be the anticipated results? Multiple Choice Cytosines in or near the promoter region will be methylated Cytosines in or near the promoter will not be methylated Cytosines in the coding region will have an increased methylation There will be no differences in the methylation pattern of the promoter of p53 from a cancer cell and a normal cell

Cytosines in or near the promoter region will be methylated

It is possible that the effects of the association of the ICR and DMR regions with the CTC factors could be distance dependent. An experimental outline could be devised where the effects of the distances of these regions could be varied and the rates of transcription could be measured. Below is a graph of some possible results. Which letter represents the most likely outcome if an increase in distance between these two regions results in a diminished effect on transcription rates. Multiple Choice A B C D

D point at end of curve

A common way of studying methylation in cells is to sequence DNA samples before and after modification with sodium bisulfite. The sodium bisulfite deaminates Cytosine residues, generating Uracil residues, therefore resulting in a change in the sequence as compared to the non-modified DNA. Sodium bisulfite does not react with 5-methylcytosine so there will be no change in the sequence of those modified bases. When tumors are sequenced to study methylation patterns and epigenetic control, what would be the best control for sequencing using this technique? Multiple Choice Non-cancerous tissue DNA from a different individual but from the same organ Liver DNA from the same individual that the cancer sample is from DNA from non-cancerous tissue from the same individual's organ as the cancer A combination of DNA from liver, brain and muscle from the same individual that has the cancer

DNA from non-cancerous tissue from the same individual's organ as the cancer

Which of the following statements are correct? Multiple Choice Changes in gene expression based on environmental conditions are not considered normal while developmental changes are Environmental epigenetic changes can vary due to the exposure of the organism to different environmental conditions, while those programmed during development are the result of stimuli generated by the organism itself Environmental epigenetic gene regulation only occurs in reptiles and insects, while developmental epigenetic regulation occurs in all animals Environmental epigenetic gene regulation is typically reversible while developmental epigenetic gene regulation is typically not reversible.

Environmental epigenetic changes can vary due to the exposure of the organism to different environmental conditions, while those programmed during development are the result of stimuli generated by the organism itself

Which of the following is an example of epigenetic inheritance Multiple Choice Expression of the Igf-2 gene based on methylation of the ICR and DMR regions Inheritance of flower color as studied by Mendel Leaf coloration based on mitochondrial inheritance Snail shell twist patterns

Expression of the Igf-2 gene based on methylation of the ICR and DMR regions

The differentially methylated region (DMR) is associated with which of the following? Multiple Choice X-inactivation Genomic imprinting Maternal inheritance Extra nuclear inheritance All of the answers are correct

Genomic imprinting

The expression of a single allele is associated with which of the following? Multiple Choice X-inactivation Genomic imprinting Maternal inheritance Extra nuclear inheritance

Genomic imprinting

Most imprinted genes are silenced. What is one exception to this rule? Multiple Choice H19 Igf-2 UBE3A SNRPN

Igf-2

What is the molecular mechanism for imprinting a gene? Multiple Choice Acetylation Nitration Phosphorylation Methylation

Methylation

In the Igf-2 allele, which chromosome is imprinted? Which is expressed? Multiple Choice Paternal, paternal Paternal, maternal Maternal, paternal Maternal, maternal

Paternal, paternal

Gene methylation can be detected through the use of restriction endonucleases. Usually these are used in pairs where one enzyme will digest only unmethylated DNA in its recognition sequence while the other is insensitive to methylation. Which of the following statements is correct? Multiple Choice The enzyme that is insensitive to methylation serves as a control to make sure the inability of the other enzyme to digest DNA is not due to a mutation. These are used in pairs since experiments have to be replicated and this one way of performing a replication of the experiment The experimental design is flawed since there should be a third enzyme that would serve as a positive control This experimental design is able to detect most of the methylated C residues in a particular region of DNA.

The enzyme that is insensitive to methylation serves as a control to make sure the inability of the other enzyme to digest DNA is not due to a mutation.

What is the difference between the trithorax (TrxG) and polycomb (PcG) complexes of proteins? Multiple Choice TrxG proteins methylate lysine 27 on histone H3 while PcG complexes methylate lysine 4 on H3 Methylation of lysine at position 4 on H3 results in silencing of gene expression TrxG complex proteins activate gene expression by methylating lysine 4 on H3, while PcG complex proteins repress gene expression by methylating lysine 27 on H3. Methylation of H3 on lysine 27 can result in activation of transcription

TrxG complex proteins activate gene expression by methylating lysine 4 on H3, while PcG complex proteins repress gene expression by methylating lysine 27 on H3.

Expression of ______ would inhibit X-inactivation. Multiple Choice Xic Xist Tsix All of the answers are correct None of the answers are correct

Tsix

What gene is most responsible for X-inactivation? Multiple Choice Xic Xist Tsix Xce

Xist

What genes appear to be controlled by the Xic? Multiple Choice Xist and Tsix Xist TsiX Xic

Xist and Tsix

A modification that occurs to a nuclear gene that alters gene expression, but not permanently, is called _______ inheritance. Multiple Choice extranuclear cytoplasmic maternal effect epigenetic nuclear

epigenetic