Deck 21: Epigenetics

Question 1

Which of the following is NOT true of honeybees?

A) Queen bees and worker bees are both female.
B) Worker bees are smaller than queen bees.
C) Queen bees develop by being fed royal jelly.
D) Worker bees produce eggs to maintain the hive population.
E) Queen bees and worker bees are genetically identical.

Answer 1

D

Question 2

How would you expect DNA methylation to alter gene expression?

A) greatly increase expression
B) moderately increase expression
C) no change in expression
D) measurably decrease expression
E) either increase or decrease expression

Answer 2

D

Question 3

What characteristic of DNA allows methylation patterns to be maintained through replication and cell division?

A) semiconservative replication
B) recombination and repair
C) the absence of uracil
D) topoisomerases
E) deoxyribonucleotide synthesis

Answer 3

A

Question 4

What histone modifications are associated with DNA repair?

A) H3K27 acetylation
B) H3K79 methylation
C) H2B ubiquitination
D) H3K27 acetylation and H2B ubiquitination
E) H3K79 methylation and H2B ubiquitination

Question 5

Which of the following is NOT an example of epigenetics?

A) independent assortment of alleles
B) genomic imprinting
C) miRNAs
D) paramutation
E) X inactivation

Question 6

What effect does histone acetylation have on transcription?

A) decreases expression
B) decreases translation but not transcription
C) no change in expression
D) increases expression
E) either increases or decreases expression

Question 7

What type of enzyme would MOST likely promote increased gene expression?

A) DNA methyltransferase
B) DNA demethylase
C) DNA polymerase
D) DNA ligase
E) DNAse

Question 8

Which of the following is an example of "crosstalk" in epigenetics?

A) DNA methylation leads to histone deacetylation.
B) DNA methylation leads to histone acetylation.
C) H2B ubiquitination leads to H3K79 methylation.
D) DNA methylation leading to either histone acetylation or deacetylation.
E) DNA methylation leads to histone acetylation and H2B ubiquitination leads to H3K79 methylation.

Question 9

List three types of molecular mechanisms that alter chromatin structure and underlie many epigenetic phenotypes.

Question 10

You are a researcher trying to understand the epigenetic mechanisms of queen bee development. Which of the following experimental manipulations would probably NOT lead to the development of a queen bee?

A) Feeding royal jelly to a female honeybee larva
B) Feeding decitabine, a DNA methyltransferase inhibitor, to a female larva
C) Injecting Dnmt3 siRNA into a female honeybee larva
D) Activation of a DNA cytosine deaminase enzyme in a female larva
E) Feeding royal jelly to an adult worker honeybee

Question 11

What effect would the deamination of 5-methylcytosine in a promoter have on the expression of that gene?

A) The gene will have increased expression because this chemical reaction will result in unmethylated cytosine.
B) The gene will have increased expression because this chemical reaction will result in thymine.
C) The gene will have increased expression because this chemical reaction will result in uracil.
D) The gene will have decreased expression because this chemical reaction will result in unmethylated cytosine.
E) The gene will have decreased expression because this chemical reaction will result in uracil.

Question 12

A beekeeper notices that her bee population is declining rapidly. Upon further study, she notices that there are no queen bees present in her population. She suspects this is due to exposure to an environmental agent. Which of the following could be a possible mechanism for the environmental agent?

A) The environmental agent inhibits Dnmt3.
B) The environmental agent causes royal jelly to be produced in abnormally high amounts.
C) The environmental agent mimics a Dnmt3 siRNA.
D) The environmental agent is causing extensive chromosome rearrangements within the genome of the queen bees.
E) The environmental agent is a methyltransferase enzyme that acts on genes that encode queen bee characteristics.

Question 13

Which of the following statements is NOT true of DNA methylation?

A) It is associated with transcription repression.
B) It occurs on cytosines adjacent to guanines.
C) Cytosines on both strands are usually methylated.
D) It is carried out by DNA methyltransferases.
E) Methylation is permanent and cannot be reversed.

Question 14

Explain how DNA methylation is passed on to daughter cells.

Question 15

The promoter of gene A has histones that are acetylated on lysine 27 of histone H3, and the promoter of gene B has histones that are methylated on lysine 4 of histone H3. Which gene is being actively transcribed?

A) gene A, because histone acetylation is associated with gene expression
B) gene A, because histone acetylation is associated with gene silencing
C) gene B, because histone methylation is associated with gene expression
D) gene B, because histone acetylation is associated with gene silencing
E) Both genes are actively transcribed because both of those marks are associated with gene expression.

Question 16

How does histone acetylation affect chromatin structure?

A) neutralizes positive histone charges and results in more tightly packed chromatin
B) neutralizes negative histone charges and results in more tightly packed chromatin
C) increases positive histone charges and results in more tightly packed chromatin
D) neutralizes positive histone charges and results in more loosely packed chromatin
E) neutralizes negative histone charges and results in more loosely packed chromatin

Question 17

Consider a hypothetical gene in mice called the can gene. The mutant form of this gene causes skin cancer and behaves in a dominant manner. A mouse with skin cancer was studied to determine the location of the mutation in the can gene. However, when scientists sequenced both maternal and paternal copies of the gene, they could not identify any mutation in the gene. What is a possible explanation for the mouse's skin cancer?

A) One of the copies of the can gene could be hypermethylated and thus transcriptionally inactive in the mouse.
B) One of the copies of the can gene could have an inversion that renders it nonfunctional.
C) Both copies of the can gene must have the exact same mutation and, therefore, the sequencing reaction could not detect the location of the mutation.
D) One of the copies of the can gene could be deacetylated and thus transcriptionally inactive in the mouse.
E) The only possible explanation is that it is a different gene at a different locus that is causing the skin cancer in the mouse.

Question 18

Kit⁺Kit⁺ mice were crossed with Kit⁺Kit^t mice. The embryos resulting from this cross were then injected with miRNAs specific to Kit mRNA. What phenotype will these embryos develop to have?

A) All mice will have the wild-type phenotype.
B) All mice will have the mutant phenotype.
C) The Kit⁺Kit⁺ mice will have the wild-type phenotype, and the Kit⁺Kit^t mice will have the mutant phenotype.
D) The Kit⁺Kit⁺ mice will have more mutant phenotypes than wild-type phenotypes, and the Kit⁺Kit^t mice will have the mutant phenotype.
E) The Kit⁺Kit⁺ mice will have the wild-type phenotype, and the Kit⁺Kit^t mice will have a 1:1 ratio of the wild-type to mutant phenotype.

Question 19

What do you expect would develop if you injected Dnmt3 siRNA into honeybee larvae?

A) a male drone
B) a female worker
C) a female queen
D) a male drone or a female worker
E) a female worker or a queen

Question 20

What is the molecular basis of the epigenetic effect of royal jelly?

A) inhibits Dnmt3, causes less DNA methylation
B) inhibits Dnmt3, causes more DNA methylation
C) inhibits Hdac3, causes less histone acetylation
D) inhibits Dnmt3, causes less histone methylation
E) inhibits Dnmt3, causes more histone methylation

Question 21

When does paternal X inactivation occur in mice? (Select all that apply.)

A) at fertilization
B) 8-cell stage of embryo
C) blastocyst maturation
D) at birth
E) within 10 days after birth

Question 22

When does maternal X inactivation occur in mice?

A) at fertilization
B) 8-cell stage of embryo
C) blastocyst maturation
D) at birth
E) within 10 days after birth

Question 23

Which of the following inhibits the expression of Xist on the inactive X chromosome?

A) Xist
B) Tsix
C) Jpx
D) Xite
E) Xist expression is not inhibited on the inactive X chromosome.

Question 24

Which of the following is NOT a characteristic of imprinted loci?

A) Some imprinted alleles have biased expression, rather than being all on or off.
B) Imprinting occurs in clusters of 3 to 12 genes.
C) Imprinted loci contain protein-coding and noncoding RNA genes.
D) Imprinted loci occur on sex chromosomes but not on autosomes.
E) Some alleles are imprinted only in certain tissues or at certain times of development.

Question 25

Which of the following stimulates the transcription of Xist on the active X chromosome?

A) Xist
B) Tsix
C) Jpx
D) Xite
E) Xist is not transcribed on the active X chromosome.

Question 26

Which of the following stimulates the transcription of Xist on the inactive X chromosome?

A) Xist
B) Tsix
C) Jpx
D) Xite
E) Xist is not transcribed on the inactive X chromosome.

Question 27

How is the epigenetic trait induced by vinclozolin transmitted to offspring?

A) DNA methylation is increased in sperm of treated males, and this methylation pattern is inherited by offspring.
B) Treated males are more successful at mating, so more offspring inherit the trait.
C) Females exposed to the drug produce fewer eggs, and the resulting offspring exhibit this same phenotype.
D) Treated females have increased DNA methylation in neuronal cells, which alters their mating behaviors.

Question 28

How do epigenetic marks compare in monozygotic twins?

A) They are similar early in life but are increasingly dissimilar with age.
B) They are different at birth, but a similar environment during childhood causes them to become more similar with time.
C) They stay the same throughout their lives because monozygotic twins are genetically identical.
D) DNA methylation patterns are similar, but histone acetylation patterns are very different.

Question 29

A group of scientists is studying memory in mice. They feed sodium butyrate, a histone deacetylase inhibitor, to a group of older mice and then subject them to memory exercises. How do you predict the memory of treated mice might compare with the memory of untreated mice?

A) Histone acetylation increases with age, so sodium butyrate may improve memory in older mice.
B) Histone acetylation increases with age, so sodium butyrate may impair memory in older mice.
C) Histone acetylation decreases with age, so sodium butyrate may improve memory in older mice.
D) Histone acetylation decreases with age, so sodium butyrate may impair memory in older mice.
E) Histone acetylation is not associated with memory in mice.

Question 30

Which statement BEST described how imprinting varies over the course of development?

A) Imprinted alleles are permanently silenced from embryo development through adulthood.
B) Imprinting is only active during embryo development, but expression returns to normal during adulthood.
C) Imprinting is only active during gametogenesis, where alleles are selectively silenced before being transmitted to offspring.
D) Imprinting randomly flickers on and off during development.
E) Imprinted alleles differ by tissue type and time of development.

Question 31

How does the DNA methylation pattern compare between embryonic stem cells, somatic cells, and induced pluripotent stem cells?

A) Embryonic stem cells show the highest amount of DNA methylation, while somatic cells show the lowest.
B) Embryonic stem cells show the highest amount of DNA methylation, while induced pluripotent stem cells show the lowest.
C) Induced pluripotent stem cells have less DNA methylation than differentiated cells but more than embryonic stem cells.
D) Induced pluripotent stem cells show the highest amount of DNA methylation, while somatic cells show the lowest.
E) Somatic cells show the highest amount of DNA methylation, while induced pluripotent stem cells show the lowest.

Question 32

How long is Xist RNA?

A) 21 bp
B) 500 bp
C) 1500 bp
D) 17,000 bp
E) 230,000 bp

Question 33

How does DNA methylation contribute to the repression of transcription?

Question 34

Which of the following inhibits the expression of Xist on the active X chromosome?

A) Xist
B) Tsix
C) Jpx
D) Xite
E) X-inactivation center

Question 35

How does genomic imprinting affect gene expression?

A) increases expression of imprinted alleles
B) lowers expression of imprinted alleles
C) completely silences expression of imprinted alleles
D) increase of decrease expression of imprinted alleles, depending on the situation
E) Genomic imprinting can lower the expression of imprinted alleles or completely silence them.

Question 36

What type of RNA is Xist?

A) lncRNA
B) mRNA
C) rRNA
D) siRNA
E) tRNA

Question 37

Which of the following is NOT a defining feature of paramutation?

A) The expression pattern is transmitted to future generations.
B) The altered allele is able to convert other alleles.
C) No DNA sequence differences exist between alleles.
D) Mutation of coding sequences generates new alleles.
E) These are all defining features of paramutation.

Question 38

What epigenetic marks occur during X inactivation?

A) H3K27 acetylation
B) H3K79 methylation
C) H2B ubiquitination
D) H3K27 methylation
E) H3S10 phosphorylation

Question 39

What protein factors are recruited by Xist that causes epigenetic silencing of the X chromosome?

A) RNA polymerases
B) DNA polymerases
C) polycomb group proteins
D) histone acetyltransferases
E) DNA demethylases

Question 40

Which of the following stimulates the transcription of Tsix on the active X chromosome?

A) Xist
B) Tsix
C) Jpx
D) Xite
E) Tsix is not transcribed on the active X chromosome.

Question 41

Use the following to answer questions
You are studying epigenetic regulation of the Bdnf gene in mice and its association with memory. You train mouse B to avoid an adverse stimulus and then isolate genomic DNA from its brain. Mouse A is untrained and used as a control. You take the brain DNA samples and split each of them into two parts. One part is treated with sodium bisulfite and the other part is left untreated. You then perform PCR for the Bdnf locus and digest the PCR product with the restriction enzyme AccII that cuts DNA at the sequence CGCG. The digested DNA is then separated by agarose gel electrophoresis to obtain the following DNA fragments:
$$\begin{array}{l}\begin{array} { c c } \text { Mouse A (Bisulfite DNA) } & \text { Mouse A (Untreated DNA) } \\\hline 21.2 \mathrm {~kb} & 19.3 \mathrm {~kb} \\7.4 \mathrm {~kb} & 7.4 \mathrm {~kb} \\5.8 \mathrm {~kb} & 5.1 \mathrm {~kb} \\5.7 \mathrm {~kb} & 3.9 \mathrm {~kb} \\4.9 \mathrm {~kb} & 3.5 \mathrm {~kb} \\3.5 \mathrm {~kb} & 2.7 \mathrm {~kb} \\& 2.2 \mathrm {~kb} \\& 1.9 \mathrm {~kb} \\& 1.8 \mathrm {~kb} \\& 0.7 \mathrm {~kb}\end{array}\\\\\begin{array} { c c } \text { Mouse B (Bisulfite DNA) } & \text { Mouse B (Untreated DNA) } \\\hline 19.3 \mathrm {~kb} & 19.3 \mathrm {~kb} \\7.4 \mathrm {~kb} & 7.4 \mathrm {~kb} \\5.7 \mathrm {~kb} & 5.1 \mathrm {~kb} \\5.1 \mathrm {~kb} & 3.9 \mathrm {~kb} \\4.9 \mathrm {~kb} & 3.5 \mathrm {~kb} \\3.5 \mathrm {~kb} & 2.7 \mathrm {~kb} \\1.9 \mathrm {~kb} & 2.2 \mathrm {~kb} \\0.7 \mathrm {~kb} & 1.9 \mathrm {~kb} \\& 1.8 \mathrm {~kb} \\& 0.7 \mathrm {~kb}\end{array}\end{array}$$

-What can you conclude about the epigenetic effect of learning on the Bdnf locus in mice?

A) DNA methylation decreases, causing a decrease in Bdnf expression.
B) DNA methylation increases, causing a decrease in Bdnf expression.
C) DNA methylation decreases, causing an increase in Bdnf expression.
D) DNA methylation increases, causing an increase in Bdnf expression.
E) DNA methylation does not alter Bdnf expression.

Question 42

Which of the following is NOT true of bisulfite sequencing?

A) Methylated cytosines are unaffected by sodium bisulfite.
B) DNA is treated with sodium bisulfite, which chemically converts unmethylated cytosines to uracil.
C) Unmethylated cytosines are detected as thymine during sequencing.
D) All thymines revealed in DNA sequencing of bisulfite treated DNA were cytosines in the original, untreated DNA.
E) The sequence of genomic DNA treated with sodium bisulfite is compared to the sequence of untreated genomic DNA.

Question 43

Which of the following is NOT affected by genomic imprinting?

A) Angelman syndrome
B) Prader-Willi syndrome
C) Beckwith-Wiedemann syndrome
D) Igf2 alleles in mice
E) Down syndrome

Question 44

You are scientist who studies the epigenetic effects of maternal behavior in rats. Which of the following experimental manipulations will lead to an INCREASED stress response in young rats whose mothers lick and groom them?

A) injection of glucocorticoid agonist (that would stimulate the glucocorticoid receptor) into young rat brains
B) injection of histone deacetylase inhibitors into young rat brains
C) injection of DNA demethylase inhibitors into young rat brains
D) feeding glucocorticoid receptor inhibitors during early postnatal development

Question 45

In corn, red kernels (PP) are typically dominant to white kernels (pp). A red plant was crossed with a white plant to produce a Pp heterozygote with red kernels. However, in one ear of corn, a partially white kernel appeared unexpectedly. This kernel was grown into an adult plant, and for several generations of crosses, the offspring of this original kernel all had a mix of partially red and partially white kernels. However, when the seeds were grown in the presence of a demethylating drug, all of the resulting plants had red kernels. Explain why the mixed-color kernel appeared, why the offspring of this kernel also had the mixed-color phenotype, and why the demethylating drug had its effect.

Question 46

Describe three important features that define paramutation.

Question 47

Compare the effects of the environment on the epigenetics of glucocorticoid receptor expression in mice and humans.

Question 48

Consider a gene in mice that is normally maternally imprinted. If a deletion occurred in the gene, rendering it nonfunctional, what would be the expected phenotypic result?

A) If the mutation occurred in the maternal copy of the gene, the mouse would be wild-type, but if the mutation occurred in the paternal copy of the gene, the mouse would be mutant.
B) If the mutation occurred in the maternal copy of the gene, the mouse would be mutant, but if the mutation occurred in the paternal copy of the gene, the mouse would be wild type.
C) If the gene behaves in a dominant manner, the mouse would be mutant, but if the gene behaves in a recessive manner, the mouse would be wild type.
D) Because the gene is maternally imprinted, all female mice would be mutant, but all male mice would be wild type.
E) Because the gene is maternally imprinted, all female mice would be wild type, but all male mice would be mutant.

Question 49

Explain how studies in mice suggest that diet can cause epigenetic changes that are transmitted through generations.

Question 50

Use the following to answer questions
You are studying epigenetic regulation of the Bdnf gene in mice and its association with memory. You train mouse B to avoid an adverse stimulus and then isolate genomic DNA from its brain. Mouse A is untrained and used as a control. You take the brain DNA samples and split each of them into two parts. One part is treated with sodium bisulfite and the other part is left untreated. You then perform PCR for the Bdnf locus and digest the PCR product with the restriction enzyme AccII that cuts DNA at the sequence CGCG. The digested DNA is then separated by agarose gel electrophoresis to obtain the following DNA fragments:
$$\begin{array}{l}\begin{array} { c c } \text { Mouse A (Bisulfite DNA) } & \text { Mouse A (Untreated DNA) } \\\hline 21.2 \mathrm {~kb} & 19.3 \mathrm {~kb} \\7.4 \mathrm {~kb} & 7.4 \mathrm {~kb} \\5.8 \mathrm {~kb} & 5.1 \mathrm {~kb} \\5.7 \mathrm {~kb} & 3.9 \mathrm {~kb} \\4.9 \mathrm {~kb} & 3.5 \mathrm {~kb} \\3.5 \mathrm {~kb} & 2.7 \mathrm {~kb} \\& 2.2 \mathrm {~kb} \\& 1.9 \mathrm {~kb} \\& 1.8 \mathrm {~kb} \\& 0.7 \mathrm {~kb}\end{array}\\\\\begin{array} { c c } \text { Mouse B (Bisulfite DNA) } & \text { Mouse B (Untreated DNA) } \\\hline 19.3 \mathrm {~kb} & 19.3 \mathrm {~kb} \\7.4 \mathrm {~kb} & 7.4 \mathrm {~kb} \\5.7 \mathrm {~kb} & 5.1 \mathrm {~kb} \\5.1 \mathrm {~kb} & 3.9 \mathrm {~kb} \\4.9 \mathrm {~kb} & 3.5 \mathrm {~kb} \\3.5 \mathrm {~kb} & 2.7 \mathrm {~kb} \\1.9 \mathrm {~kb} & 2.2 \mathrm {~kb} \\0.7 \mathrm {~kb} & 1.9 \mathrm {~kb} \\& 1.8 \mathrm {~kb} \\& 0.7 \mathrm {~kb}\end{array}\end{array}$$

-How many of the AccII sites were methylated at the Bdnf locus in the trained mouse?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 51

Explain how the b1 locus in corn exhibits paramutation.

Question 52

Explain how bisulfite sequencing helps researchers to detect methylated cytosines.

Question 53

Use the following to answer questions
You are studying epigenetic regulation of the Bdnf gene in mice and its association with memory. You train mouse B to avoid an adverse stimulus and then isolate genomic DNA from its brain. Mouse A is untrained and used as a control. You take the brain DNA samples and split each of them into two parts. One part is treated with sodium bisulfite and the other part is left untreated. You then perform PCR for the Bdnf locus and digest the PCR product with the restriction enzyme AccII that cuts DNA at the sequence CGCG. The digested DNA is then separated by agarose gel electrophoresis to obtain the following DNA fragments:
$$\begin{array}{l}\begin{array} { c c } \text { Mouse A (Bisulfite DNA) } & \text { Mouse A (Untreated DNA) } \\\hline 21.2 \mathrm {~kb} & 19.3 \mathrm {~kb} \\7.4 \mathrm {~kb} & 7.4 \mathrm {~kb} \\5.8 \mathrm {~kb} & 5.1 \mathrm {~kb} \\5.7 \mathrm {~kb} & 3.9 \mathrm {~kb} \\4.9 \mathrm {~kb} & 3.5 \mathrm {~kb} \\3.5 \mathrm {~kb} & 2.7 \mathrm {~kb} \\& 2.2 \mathrm {~kb} \\& 1.9 \mathrm {~kb} \\& 1.8 \mathrm {~kb} \\& 0.7 \mathrm {~kb}\end{array}\\\\\begin{array} { c c } \text { Mouse B (Bisulfite DNA) } & \text { Mouse B (Untreated DNA) } \\\hline 19.3 \mathrm {~kb} & 19.3 \mathrm {~kb} \\7.4 \mathrm {~kb} & 7.4 \mathrm {~kb} \\5.7 \mathrm {~kb} & 5.1 \mathrm {~kb} \\5.1 \mathrm {~kb} & 3.9 \mathrm {~kb} \\4.9 \mathrm {~kb} & 3.5 \mathrm {~kb} \\3.5 \mathrm {~kb} & 2.7 \mathrm {~kb} \\1.9 \mathrm {~kb} & 2.2 \mathrm {~kb} \\0.7 \mathrm {~kb} & 1.9 \mathrm {~kb} \\& 1.8 \mathrm {~kb} \\& 0.7 \mathrm {~kb}\end{array}\end{array}$$

-How many of the AccII sites were methylated at the Bdnf locus in the untrained mouse?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 54

In a female human cell, what would be the effect on X inactivation if a mutation occurred in the Xist gene making it nonfunctional?

A) One of the two X chromosomes would become inactivated.
B) Both of the X chromosomes would become inactivated.
C) Neither of the X chromosomes would become inactivated.
D) Only the maternal X chromosome would become inactivated.
E) Only the paternal X chromosome would become inactivated.

Question 55

Use the following to answer questions
You are studying epigenetic regulation of the Bdnf gene in mice and its association with memory. You train mouse B to avoid an adverse stimulus and then isolate genomic DNA from its brain. Mouse A is untrained and used as a control. You take the brain DNA samples and split each of them into two parts. One part is treated with sodium bisulfite and the other part is left untreated. You then perform PCR for the Bdnf locus and digest the PCR product with the restriction enzyme AccII that cuts DNA at the sequence CGCG. The digested DNA is then separated by agarose gel electrophoresis to obtain the following DNA fragments:
$$\begin{array}{l}\begin{array} { c c } \text { Mouse A (Bisulfite DNA) } & \text { Mouse A (Untreated DNA) } \\\hline 21.2 \mathrm {~kb} & 19.3 \mathrm {~kb} \\7.4 \mathrm {~kb} & 7.4 \mathrm {~kb} \\5.8 \mathrm {~kb} & 5.1 \mathrm {~kb} \\5.7 \mathrm {~kb} & 3.9 \mathrm {~kb} \\4.9 \mathrm {~kb} & 3.5 \mathrm {~kb} \\3.5 \mathrm {~kb} & 2.7 \mathrm {~kb} \\& 2.2 \mathrm {~kb} \\& 1.9 \mathrm {~kb} \\& 1.8 \mathrm {~kb} \\& 0.7 \mathrm {~kb}\end{array}\\\\\begin{array} { c c } \text { Mouse B (Bisulfite DNA) } & \text { Mouse B (Untreated DNA) } \\\hline 19.3 \mathrm {~kb} & 19.3 \mathrm {~kb} \\7.4 \mathrm {~kb} & 7.4 \mathrm {~kb} \\5.7 \mathrm {~kb} & 5.1 \mathrm {~kb} \\5.1 \mathrm {~kb} & 3.9 \mathrm {~kb} \\4.9 \mathrm {~kb} & 3.5 \mathrm {~kb} \\3.5 \mathrm {~kb} & 2.7 \mathrm {~kb} \\1.9 \mathrm {~kb} & 2.2 \mathrm {~kb} \\0.7 \mathrm {~kb} & 1.9 \mathrm {~kb} \\& 1.8 \mathrm {~kb} \\& 0.7 \mathrm {~kb}\end{array}\end{array}$$

-How many AccII sites are found at the Bdnf locus?

A) 4
B) 6
C) 9
D) 10
E) 16