Chapter 16: Gene Regulation in Eukaryotes II: Epigenetics
The variation of gene expression that is not related to the variation of the DNA, is transmissible, and is reversible is described as __________.
epigenetics
The inactivation of an X chromosome occurs in ______.
female mammals
A paramutation is a ______.
genetic interaction in which one allele induces a heritable change in the other allele
After vernalization, plants ______.
have the ability to flower when conditions are favorable. have acquired epigenetic modifications in their genome.
Before replication, a heterochromatic region has sites with fully methylated DNA and nucleosomes with H3K9me3 histone modifications. After DNA replication, what would be the constituents of each daughter chromatid?
hemimethylated DNA half of the H3 histones with H3K9me3 modifications
The methylation of hemimethylated sites is called ______.
maintenance methylation
The formation of heterochromatin begins at a(n)_____________site, continues by__________in both directions, and stops when a(n)________site is reached.
nucleation spreading barrier
Put the phases of heterochromatin formation in the correct order, placing the earliest event at the top.
nucleation spreading reaching a barrier
The basic repeating unit of chromatin is the________, composed of_________wrapped around an octamer of ___________proteins.
nucleosome DNA histone
In maize, the dominant allele B-I encodes a transcription factor that regulates genes involved in producing purple color of corn stalks and husks. The allele can undergo a mutation to B' which changes the stalk and husk color from purple to green. In a cross between B-I B-I and B' B' homozygotes, the F1 heterozygotes all have green stalks and husks. This shows that the B' allele is____________ and the B-I allele is______________.
paramutagenic paramutable
A________________ occurs when one allele of a gene induces a heritable change in the other allele without altering the DNA sequence.
paramutation
Mice that are homozygous for the loss-of-function mutation in the Agouti gene will have black fur because ______.
pheomelanin is not produced
Multiple tandem repeat sequences near paramutagenic alleles may be involved in paramutation by ______.
producing siRNAs to reduce expression
Female honeybee larvae fed and bathed in royal jelly during development will become ______ bees.
queen
In studies analyzing the development of honeybees, those bees that were injected with a substance inhibiting DNA methyltransferase, and were fed the diet of worker bees developed as ______.
queen
In maize, the dominant allele B-I codes for a transcription factor that regulates genes involved in producing purple color in corn stalks and husks. The allele can undergo a mutation to B' which changes the stalk and husk color from purple to green. In a cross between B-I B-I and B' B' homozygotes, the F1 heterozygotes all have green stalks and husks. When these F1 individuals are crossed to B-I B-I homozygotes, all of the F2 offspring have green stalks and husks. The results for the F2 generation demonstrate a ______ paramutation of the ______ allele.
secondary; B-I allele.
In mice, the Agouti gene regulates ______.
the deposition of yellow pigment in hair
During embryonic development, many genes within a specific cell type will undergo epigenetic changes that enable them to be_____________ or cause them to be permanently ___________.
transcribed repressed
Which one best represents the current model of how cold temperatures cause repression of the FLC gene?
Cold temperatures induce expression of a non-coding RNA, COLDAIR, which recruits a chromatin modifying complex to FLC
M phase through interphase in two daughter cells
Constitutive and facultative heterochromatin regions retain the same pattern observed in mother cell.
Which of the following are examples of epigenetics?
DNA methylation Localization of histone variants Covalent histone modification Chromatin remodeling
What accounts for the variation in coat color in the mice shown?
Degree of methylation at CpG islands in the TE upstream from the Agouti gene
Which of the following are true regarding epigenetics?
Epigenetic changes are transmissible from cell to cell Variations are reversible from one generation to the next Epigenetic changes may be transmitted to offspring Variations of gene expression are unrelated to variations in the DNA base sequence
Identify changes that can occur during embryonic development that will lead to a pattern of differential gene expression unique to a specific cell type.
Epigenetic changes that cause specific genes to be permanently repressed Epigenetic changes that enable specific genes to be transcribed
M phase
Euchromatic regions condense into constitutive and facultative heterochromatin.
The protein ______ which represses genes required for flowering in the winter-annual type of Arabidopsis, is inhibited by prolonged exposure to cold.
FLC
Which transcription factors activate several genes that lead to flower development in the winter-annual type of Arabidopsis?
FT and SOC1
True or false: Because epigenetics refers to heritable changes in gene expression, all epigenetic changes are examples of transgenerational epigenetic inheritance.
False
Which of the following represent key functional roles for heterochromatin in eukaryotic cells?
Preventing movement of transposable elements Preventing viral proliferation Silencing genes
In eukaryotic cells, which processes are prevented by heterochromatin formation?
Viral proliferation Transcription Transposable element movement
The mop1 gene, which is required for paramutation in Arabidopsis, encodes ______ that produces siRNA for gene silencing.
an RNA-dependent RNA polymerase
Mice that are homozygous for the loss-of-function mutation in the Agouti gene will have ______ fur.
black
Genomic imprinting and X-chromosome inactivation are examples of ______ mechanisms that occur during development.
cis-epigenetic
Which type of epigenetic mechanism is shown in the image?
cis-epigenetic mechanism
Vernalization refers to a requirement for ______ before certain plants can undergo flowering.
cold
The methylation of a previously unmethylated site is called ______.
de novo methylation
A series of genetically programmed stages that begins with sperm and eggs that fuse to become an embryo that will eventually change into an adult is called ______.
development
In multicellular species, ______________involves a series of genetically programmed stages in which a fertilized egg becomes an embryo and eventually changes into an adult.
development
Most chromosomal regions are composed of euchromatin.
Interphase
The inactivation of an X chromosome is a(n) ______ event.
epigenetic
DNA methylation, chromatin remodeling, covalent histone modification, and localization of histone variants are all examples of molecular mechanisms that are involved in____________.
epigenetics
ICF syndrome and Roberts syndrome are inherited diseases associated with abnormalities in ______.
heterochromatin formation
What accounts for the wide array of coat colors seen in mice carrying the Avy allele of the Agouti gene?
Epigenetic modification of the promoter in the transposable element responsible for over expressing the Agouti gene
True or false: Gene regulation may be related to epigenetic events such as the binding of transcription factors to certain genes, which induce permanent mutations in the DNA.
False
What can be deduced about the effect of DNA methylation levels on expression of the Agouti gene?
Greater levels of methylation resulted in darker coat color.
In mammals, females (XX) and males (XY) express genes on the X chromosome at the same levels because of ______.
X chromosome inactivation
In studies analyzing the development of honeybees, bees that were injected with a substance inhibiting DNA methyltransferase developed into queen bees, despite being fed the diet of a worker bee. These results suggest that royal jelly contains substances that ______ DNA methylation.
inhibit
What conclusion can be made regarding the environmental effect of diet on the expression of the Agouti gene?
The supplemental diet influenced the expression of the Agouti gene.
How do transcription factors contribute to epigenetic modification?
Transcription factors recruit chromatin modifying proteins, such as DNA methyltransferase.
The annual flowering plant Arabidopsis thaliana has two different types. Only the ______ require vernalization for flowering.
winter annuals, which grow from fall to spring,
Order the steps in the regulation of FLC expression by exposure to cold temperatures, putting the first step at the top.
1. Prolonged cold induces expression VIN3 and COLDAIR 2. VIN3 protein and PRC2 form a complex 3. VIN3/PRC2 complex binds to COLDAIR RNA as it is transcribed from within an FLC intron 4. VIN3/PRC2 complex methylates histone H3 within the FLC gene 5. FLC gene expression is repressed
A heterochromatic region with fully methylated DNA and extensively modified histone H3 prior to DNA replication, will have ______ (the) levels of these modifications in the daughter chromatids produced after DNA replication.
1/2
Adult, wild-type mice with genotype AA for the Agouti gene will have what color coat hairs?
Brown with black tips
Which of the following is an example of epigenetic inheritance?
Methylation of DNA that occurs in an oocyte
What can be deduced about the environmental effect of diet on expression of the Agouti gene?
Offspring of females fed a supplemental diet had darker coats.
Idenfity the diseases that have been associated with abnormalities in heterochromatin formation.
Roberts syndrome ICF syndrome
Which of the following statements regarding X chromosome inactivation is true?
X chromosome inactivation occurs during embryogenesis in females.
Mice with the A^vy allele exhibit ______.
a wide array of coat colors
Besides DNA and histone proteins, ____________-_____________RNAs are a critical component of chromatin.
non coding
An RNA that does not encode a polypeptide is a(n) ______ RNA.
non-coding
Female honeybee larvae fed royal jelly during early development, and nectar or pollen later in development will become ______ bees.
worker
During cell division, from M phase in the mother cell to interphase in the resulting two daughter cells, a chromosome will usually retain the same pattern of_________________ and ___________ heterochromatin that was found in the mother cell.
constitutive facultative
In multicellular species, ___________involves a series of genetically programmed stages in which a fertilized egg becomes an embryo and eventually changes into an adult.
development
X-chromosome inactivation is an epigenetic event that occurs during ______.
embryogenesis