Chapter 16 Genetics Study Guide Questions

You are studying a summer-annual Arabidopsisplants. You identify a strain with a mutation in the VIN3 gene that renders it inactive. When do you expect this plant to flower? A) You expect the plant to flower normally. B) You do not expect the plant to flower. C) The plant will grow from fall to spring instead of spring to fall. D) These plants will flower once vernalization has occurred, but will not require favorable conditions.

A) You expect the plant to flower normally.

The differentially methylated region (DMR) is associated with which of the following? A) X-inactivation B) Genomic imprinting C) Paramutation D) Heterochromatin E) All of these choices are correct.

B) Genomic imprinting

Both parents usually imprint the same gene. ⊚true⊚false

False

After the paramutable allele is altered, its expression is the same or similar to the paramutagenic allele. ⊚true⊚false

true

What genes appear to be controlled by the Xic? A)XistandTsix B)Xist C)TsiX D)Xic

A)XistandTsix

Epigenetic inheritance may occur at which of the following stages? A) Oogenesis B) Spermatogenesis C) Embryogenesis D) All of these choices are correct.

D) All of these choices are correct.

Which of the following are molecular mechanisms used in epigenetic gene regulation? A)DNA methylation B)Covalent histone modification C)Chromatin remodeling D)All of these choices are correct.

D)All of these choices are correct.

What gene(s) is/are encoded in the Xic? A)Xce B)Xist C)Tsix D)Both theTsixandXistare genes are in the Xic region

D)Both theTsixandXistare genes are in the Xic region

Imagine all the histone H3 molecules in the cell have a mutation that changes their lysine-9 residue to an alanine. Assuming this cell could still live, what would be the result? A) The ability of the cell to form heterochromatin would be hindered. B) The ability of the cell to form euchromatin would be hindered. C) There would not be much of an effect because lysine and alanine are similar amino acids. D) The ability of the cell to imprint genes would be hindered.

A) The ability of the cell to form heterochromatin would be hindered.

Regions of chromatin that are more compact are called __________; they are usually found __________ in the nucleus. A) heterochromatin; at the periphery B) euchromatin; centrally C) heterochromatin; centrally D) euchromatin; at the periphery

A) heterochromatin; at the periphery

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

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

Mice with a paramutagenic allele of the kit gene (here called kit' ) have white feet and white spots on their tails. Mice with the paramutable kit allele have brown feet and a brown tail. If you cross mice that are homozygous for the paramutagenic allele with those that are homozygous for the paramutable allele, what will be the phenotype of the progeny? Assume that the kit' allele is very stable and very paramutagenic. A)All mice will have white feet and white spots on their tails. B)All mice will have brown feet and tails. C)Mice will be in a 3:1 ratio of white feet and white spots on their tails : brown feet and brown tails. D)Mice will be in a 1:1 ratio of white feet and white spots on their tails : brown feet and brown tails.

A)All mice will have white feet and white spots on their tails.

ICF syndrome can be caused by a mutation in the Dnmt3 gene which encodes _________. A)DNA methyltransferase B)acetyltransferase C)histone variant D)histone methyltransferase

A)DNA methyltransferase

In the Igf-2 allele, which chromosome is imprinted? Which is expressed? A)Paternal; paternal B)Paternal; maternal C)Maternal; paternal D)Maternal; maternal

A)Paternal; paternal

In a 2008 experiment, researchers fed bee larvae a diet that should produce worker bees, but also injected the larvae with a DNA methyltransferase inhibitor. Most of the larvae became what type of bee? A)Queen bees B)Worker bees C)Nurse bees D)Male bees

A)Queen bees

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? A)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. B)These are used in pairs since experiments have to be replicated and this one way of performing a replication of the experiment. C)The experimental design is flawed since there should be a third enzyme that would serve as a positive control. D)This experimental design is able to detect most of the methylated C residues in a particular region of DNA.

A)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.

Following mitosis, the two daughter cells usually have __________ pattern of facultative heterochromatin and __________ pattern of constitutive heterochromatin as was present in the mother cell. A)the same; the same B)the same; a different C)a different; the same D)a different; a different

A)the same; the same

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

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

What gene is most responsible for X-inactivation? A) Xic B) Xist C) Tsix D) Xce

B) Xist

CpG islands are associated with which of the following? A)Nucleosome location B)DNA methylation C)Steroid hormone activity D)Termination of translation

B)DNA methylation

Which of the following statements are correct? A)Changes in gene expression based on environmental conditions are not considered normal while developmental changes are. B)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. C)Environmental epigenetic gene regulation only occurs in reptiles and insects, while developmental epigenetic regulation occurs in all animals. D)Environmental epigenetic gene regulation is typically reversible while developmental epigenetic gene regulation is typically not reversible.

B)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.

The expression of a single allele is associated with which of the following? A)X-inactivation B)Genomic imprinting C)Vernalization D)Heterochromatin

B)Genomic imprinting

Most imprinted genes are silenced. What is one exception to this rule? A)H19 B)Igf-2 C)Xist D)Tsix

B)Igf-2

You are studying a chromosome in a new animal species. The presence of what element would make you most confidentthat a region is facultative heterochromatin and not constitutive heterochromatin? A)DNA methylation B)LINE-type repeat sequences C)PTMs of histones D)Satellite sequences

B)LINE-type repeat sequences

You are studying a winter-annual Arabidopsisplants. You identify a strain in which the COLDAIR RNA is unstable and is degraded immediately after synthesis. When do you expect this plant to flower? A)The plant will always be able to flower. B)The plant will never be able to flower. C)These plants will flower when conditions are favorable, but will not require vernalization. D)These plants will flower once vernalization has occurred, but will not require favorable conditions.

B)The plant will never be able to flower.

You are studying a winter-annual Arabidopsisplants. You identify a strain with a mutation in the VIN3 gene that renders it inactive. When do you expect this plant to flower? A)The plant will always be able to flower. B)The plant will never be able to flower. C)These plants will flower when conditions are favorable, but will not require vernalization. D)These plants will flower once vernalization has occurred, but will not require favorable conditions.

B)The plant will never be able to flower.

You discover a new paramutagenic allele in mice that causes them to have spiky fur. You call this gene spi. Mice with the paramutagenic allele of theof the spi gene (here called spi' ) have spiky fur. Mice with the paramutable spi allele have normal flat fur. You also find that the paramutation rate of this allele is only 40%, that is, it only causes paramutation 40% of the time. If you cross mice that are homozygous for the paramutagenic allele with those that are homozygous for the paramutable allele, what will be the phenotype of the progeny? Assume that the spi' allele is very stable, and that, if not paramutated, spi is dominant to spi'. A) All of the mice will have spiky fur. B) All of the mice will have flat fur. C) 40% of the mice will have spiky fur and 60% will have flat fur. D) 60% of the mice will have spiky fur and 40% will have flat fur.

C) 40% of the mice will have spiky fur and 60% will have flat fur.

What is the difference between the trithorax (TrxG) and polycomb (PcG) complexes of proteins? A) TrxG proteins methylate lysine 27 on histone H3 while PcG complexes methylate lysine 4 on H3. B) Methylation of lysine at position 4 on H3 results in silencing of gene expression. C) 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. D) Methylation of H3 on lysine 27 can result in activation of transcription.

C) 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. A)Xic B)Xist C)Tsix

C)Tsix

A modification that occurs to a nuclear gene that alters gene expression, but not permanently, is called _______ inheritance. A)extranuclear B)cytoplasmic C)epigenetic D)nuclear

C)epigenetic

What is the molecular mechanism for imprinting a gene? A)Acetylation B)Nitration C)Phosphorylation D)Methylation

D)Methylation

In Arabidopsis, the FLC gene is necessary to promote flower development. ⊚true⊚false

False

In maize red1' is a strongly expressed allele that is paramutable. ⊚true⊚false

False

Covalent histone modification is sometimes involved in cell differentiation. ⊚true⊚false

True

Research suggests that the silencing of paramutagenic may involve short RNAs incorporated into RNA-induced silencing complexes. ⊚true⊚false

True

The red1'allele is said to beparamutagenic,because it can change the expression of another allele. ⊚ true ⊚ false

True

The trimethylation of lysine 27 in histone H3(H3k27) causes the repression of the FLC gene. ⊚ true ⊚ false

True

How might heterochromatin silence the expression of genes? (Check all that apply.) A)Limiting the access of activators to the DNA B)Limiting the access of general transcription factors to the DNA C)Limiting the access of coactivators to the DNA D)Limiting the access of repressors to the DNA

[A,B,C]

Feeding a specific diet to female mice may result in an increased proportion of pseudoagouti offspring if __________. A) the female carries the Avy allele B) the offspring have the genotype Avya C) the transposon at the Avylocus in the progeny is hypermethylated

[B,C]

Select the events that are part of the mechanism for epigenetic regulation of the Igf2 gene. (Choose all that apply.) A)Methylation of the H19 locus B)Methylation of the ICR and DMR domains C)Binding of CTCFs to methylated sequences D)Methylation of CTCFs

[B,C]