Deck 16: Gene Regulation in Eukaryotes Ii: Epigenetics

Question 1

Which of the following are molecular mechanisms used in epigenetic gene regulation?

A) DNA methylation
B) Covalent histone modification
C) Chromatin remodeling
D) Answers A, B, and C are correct

Answer 1

D

Question 2

The expression of a single allele is associated with which of the following?

A) X-inactivation
B) Genomic imprinting
C) Maternal inheritance
D) Extra nuclear inheritance

Answer 2

B

Question 3

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

Answer 3

B

Question 4

What gene(s) is/are encoded in the Xic?

A) Xce
B) Xist
C) Tsix
D) Both the Tsix and Xist are genes are in the Xic region

Question 5

What gene is most responsible for X-inactivation?

A) Xic
B) Xist
C) Tsix
D) Xce

Question 6

What is the molecular mechanism for imprinting a gene?

A) Acetylation
B) Nitration
C) Phosphorylation
D) Methylation

Question 7

In the Igf-2 allele, which chromosome is imprinted? Which is expressed?

A) Paternal, paternal
B) Paternal, maternal
C) Maternal, paternal
D) Maternal, maternal

Question 8

Which of the following is part of the mechanism for epigenetic regulation of the Igf-2 gene

A) Methylation of the H19 locus
B) Methylation of the ICR and DMR domains
C) Binding of CTC factors to methylated sequences
D) Answers B and C are correct
E) Answers A and C are correct

Question 9

Most imprinted genes are silenced. What is one exception to this rule?

A) H19
B) Igf-2
C) UBE3A
D) SNRPN

Question 10

Expression of ________ would inhibit X-inactivation.

A) Xic
B) Xist
C) Tsix
D) All of the answers are correct
E) None of the answers are correct

Question 11

Epigenetic inheritance may occur at which of the following stages?

A) Oogenesis
B) Spermatogenesis
C) Embryogenesis
D) All of the answers are correct

Question 12

Both parents usually imprint the same gene.

Question 13

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

Question 14

The differentially methylated region (DMR) is associated with which of the following?

A) X-inactivation
B) Genomic imprinting
C) Maternal inheritance
D) Extra nuclear inheritance
E) All of the answers are correct

Question 15

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

Question 16

What genes appear to be controlled by the Xic?

A) Xist and Tsix
B) Xist
C) TsiX
D) Xic

Question 17

How many Barr bodies would an individual with a XXY genotype possess?

A) 0
B) 1
C) 2
D) None of the answers are correct

Question 18

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.

Question 19

Which of the following is an example of epigenetic inheritance

A) Expression of the Igf-2 gene based on methylation of the ICR and DMR regions
B) Inheritance of flower color as studied by Mendel
C) Leaf coloration based on mitochondrial inheritance
D) Snail shell twist patterns

Question 20

A modification that occurs to a nuclear gene that alters gene expression, but not permanently, is called ________ inheritance.

A) extranuclear
B) cytoplasmic
C) maternal effect
D) epigenetic
E) nuclear

Question 21

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?

A) Cytosines in or near the promoter region will be methylated
B) Cytosines in or near the promoter will not be methylated
C) Cytosines in the coding region will have an increased methylation
D) There will be no differences in the methylation pattern of the promoter of p53 from a cancer cell and a normal cell

Question 22

A promoter mutation can turn a normal gene into an oncogene

Question 23

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

Question 24

In cancer cells there is typically under expression of oncogenes

Question 25

In maize red1' is a strongly expressed allele that is paramutable

Question 26

Covalent histone modification is sometimes involved in cell differentiation

Question 27

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

Question 28

Royal jelly feed to bee larvae causes hyperexpression of DNA methyltransferase

Question 29

In paramutation, the DNA sequence is changed temporarily

Question 30

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

Question 31

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.

Question 32

Lamarck is remembered for his theory of inheritance which hypothesized that physical characteristics acquired during an individuals lifetime were passed onto their offspring. How does this differ from epigenetic inheritance where the diet of the mother affects coat color of the offspring?

A) There is no difference between Lamarckian theories of inheritance and epigenetic inheritance
B) Epigenetic changes occur on a specific gene. If the mother does not carry the gene, then coat color will not be affected by diet
C) The change in coat color occurs in the offspring and not in the mother
D) Answers B and C are correct

Question 33

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?

A) Non-cancerous tissue DNA from a different individual but from the same organ
B) Liver DNA from the same individual that the cancer sample is from
C) DNA from non-cancerous tissue from the same individual's organ as the cancer
D) A combination of DNA from liver, brain and muscle from the same individual that has the cancer

Question 34

The red1' allele is said to be paramutagenic, because it can change the expression of another allele.

Question 35

If a human cell has two Barr bodies then the genotype of the individual could be

A) XXXY
B) XXXXY
C) XXY
D) XYY

Question 36

Expression of a tumor suppressor gene can be impaired if its promoted in hypermethylated

Question 37

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

Question 38

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.

A) A
B) B
C) C
D) D

Question 39

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 Avy locus in the progeny is hypermethylated
D) Answers B and C are correct