Instructions: Respond to the following questions by circling or bolding the text of the correct answers. You are allowed to use your book, your notes, and your classmates as sources to answer any question. 1. Researchers were interested in determining the relationship between social class, DNA methylation patterns, and biological markers of cardiovascular disease. Using a large pool of research subjects (i.e. people),the researchers analyzed the amount of methylation across each individual’s entire genome and also categorized each individual by age group (35-44, 45-54, or 55-64 years old) and by their “Deprivation group” (“Affluent” or “Deprived”).Results are displayed in Figure 2. Figure 2. Total DNA methylation as a percent of the entire genome across three age groups and two deprivation groups. In each category, a horizontal line indicates mean DNA methylation percentage; filled circles indicate individual data points. From McGuinness et al. 2012 International Journal of Epidemiology Which of the following is/are justifiable conclusions that can be drawn from this data? (Multiple answers may be correct, select all that are correct.) i. Status as affluent or deprived appears to be caused by differences in the methylation of DNA ii. For both deprivation groups (affluent and deprived) there is a trend of increased methylation with increasing age across all three age groups iii. Individuals in the deprived category exhibit decreased methylation compared to affluent individuals, when compared within each age group iv. There is a significant effect of “deprivation group” on the percent of DNA methylation v. There is a significant effect of “age group” on the percent of DNA methylation vi. The quantity of DNA methylation present in an individual’s genome appears to be directly correlated with increasing socio-economic status (i.e. affluent). vii. Deprived individuals likely have fewer genes silenced by DNA methylation than affluent individuals viii. Older individuals likely have fewer genes silenced by DNA methylation than younger individuals. ix. DNA methylation is silencing genes associated with stress in affluent individuals, but not silencing those genes in deprived individuals x. There is not enough information provided to make a justifiable conclusion. 2. A study conducted by Begum et al. 2013, investigated if DNA methylation of CpG (Cytosine-Guanine) sites in the genome of adolescents, was affected by maternal/paternal stress between infancy and the preschool years. The “promoter region of CpG Sites” refers to a region of DNA responsible for controlling the expression of genes (going from DNAaRNA). “Methylation of CpG Sites” refers to regions of the DNA that are not responsible for controlling the expression of genes (these regions are genes, DNA). “Maternal-All” and “Paternal All” included all the data from boys and girls in either “infancy” or “preschool”. The boxes on Figure 1., include a reference of boxes (in dark, medium, and lig.

1. Instructions: Respond to the following questions by circling or
bolding the text of the correct
answers. You are allowed to use your book, your notes, and
your classmates as sources to answer
any question.
1. Researchers were interested in determining the relationship
between social
class, DNA methylation patterns, and biological markers of
cardiovascular disease. Using a large pool of research subjects
(i.e. people),the researchers analyzed the amount of methylation
across each individual’s entire genome and also categorized
each individual by age group (35-44, 45-54, or 55-64 years old)
and by their “Deprivation group” (“Affluent” or
“Deprived”).Results are displayed in
Figure 2.
Figure 2. Total DNA methylation as a percent of the entire
genome across three
age groups and two deprivation groups. In each category, a
horizontal line
indicates mean DNA methylation percentage; filled circles
indicate individual
data points. From McGuinness et al. 2012 International Journal
of Epidemiology
Which of the following is/are justifiable conclusions that can be
drawn from this data? (Multiple
answers may be correct, select all that are correct.)
i. Status as affluent or deprived appears to be caused by
differences in the methylation of DNA
ii. For both deprivation groups (affluent and deprived) there is a
trend of increased methylation with increasing age across all
three age groups
iii. Individuals in the deprived category exhibit decreased

2. methylation compared to affluent individuals, when compared
within each age group
iv. There is a significant effect of “deprivation group” on the
percent of DNA
methylation
v. There is a significant effect of “age group” on the percent of
DNA methylation
vi. The quantity of DNA methylation present in an individual’s
genome appears to be directly correlated with increasing socio-
economic status (i.e. affluent).
vii. Deprived individuals likely have fewer genes silenced by
DNA methylation than affluent individuals
viii. Older individuals likely have fewer genes silenced by DNA
methylation than younger individuals.
ix. DNA methylation is silencing genes associated with stress in
affluent individuals, but not silencing those genes in deprived
individuals
x. There is not enough information provided to make a
justifiable conclusion.
2. A study conducted by Begum et al. 2013, investigated if DNA
methylation of CpG (Cytosine-Guanine) sites in the genome of
adolescents, was affected by maternal/paternal stress between
infancy and the preschool years. The “promoter region of CpG
Sites” refers to a region of DNA responsible for controlling the
CpG Sites” refers to regions of the DNA that are not responsible
for controlling the expression of genes (these regions are genes,
DNA). “Maternal-All” and “Paternal All” included all the data
from boys and girls in either “infancy” or “preschool”. The
boxes on Figure 1., include a
reference of boxes (in dark, medium, and light shade) that refer
to the percentage of methylated
CpG sites found in each sample, which is seen on the x-axis of
Figure 1.

3. Which choice below would be the best explanation of the results
from Figure 1 of this study?
i. There are greater CpG sites methylated due to maternal
adversity in boys during infancy, while CpG sites are
methylated less during paternal adversity in girls during
preschool.
ii. Paternal and maternal stress caused methylation of CpG sites
in boys and girls.
iii. CpG sites are methylated less often during infancy and more
often during preschool.
iv. CpG sites are methylated more in boys, due to maternal
adversity during infancy.
v. There was a greater percentage of methylation of CpG sites
vi. CpG sites are methylated less in girls, due to paternal
adversity during infancy.
vii. Greater than 5% of methylation occurred in girls during
maternal stress.
viii. Paternal stress led to a greater percentage of overall
methylation of CpG sites in girls when compared to the
percentage of methylated CpG sites due to paternal stress in
boys.
3. The hypothalamus is a region of the brain where cortisol is
produced and released. Cortisol (a type of glucocorticoid) is a
hormone released during times of stress in most vertebrate
animals like humans and mice. To deal with cortisol, a
glucocorticoid receptor (GR), which is a type of protein, binds
to cortisol. The interaction of cortisol and GR in the
hypothalamus ultimately helps humans and mice to have less
anxiety. Figure 2., represents a study that focused on the
expression of the GR protein in response to undernourishment.

4. Figure 2. Altered epigenetic expression of hippocampal GR
protein. i and j, GR protein intensity
in the hippocampus. α tubulin (positive control). Nourished (C),
and Undernourished (U).
Figure 2. Altered epigenetic expression of hippocampal GR
protein. i and j, GR protein intensity
in the hippocampus. α tubulin (positive control). Nourished (C),
and Undernourished (U).
Which option below best explains Figure 2 of this study?
i. Males produce less of the GR protein than females.
ii. Females produce less of the GR protein when undernourished
compared to males who are undernourished.
iii. Males and females produce less of the GR protein when
undernourished.
iv. Males and females under a normal diet produce equal
amounts of the GR protein.
v. Males and females produce the GR protein when nourished
and undernourished.
vi. Females and males produce the GR protein when nourished.
4. Explore the website
ttp://learn.genetics.utah.edu/content/epigenetics/rats/ and learn
about the effect of mother rats licking their pups on the
expression of GR protein and pup behavior.
Researchers wanted to determine if the epigenetic modification
(i.e. methylation) of the GR gene was inherited as an imprinted
epigenetic modification (e.g. inherited from mom due to her
traits; due to nature), or environmentally determined after birth
due to differences in a mother rat’s attentiveness (i.e. nurture).
They performed a cross-fostering experiment where pups born
to one “type” of mother were raised by that same “type” of
mother or the opposite “type” of mother. The treatment
identification codes are displayed in Table 1.
Following rearing, rat pups were allowed to reach

5. adulthood and then the GR gene DNA was tested for
methylation. Data are shown in Figure 3.
Table 1. Treatment identification codes for rats born of one
“type” of
mother but raised by another “type” of mother.
Pups born to
Pups raised by
Treatment code
Low-licking mother
Low-licking mother
L-L
High-licking mother
High-licking mother
H-H
High-licking mother
Low-licking mother
H-L
Low-licking mother
High-licking mother
L-H
Figure 3. Mean percent (± s.e.m.) of GR gene DNA that was
methylated after a cross-fostering experiment with rats. From
Weaver et al. 2004 Nature Neuroscience.
a. Which of the following is/are justifiable conclusions
based on the data in Figure 3? (Multiple answers
may be correct, select all that are correct.)
i. Rats born to low-licking mothers exhibit high levels of

6. methylation regardless of which mother raised them.
ii. Rats born to high-licking mothers exhibit high levels of
methylation regardless of which mothers raised them.
iii. Rats born to high-licking mothers exhibit low levels of
methylation regardless of which mothers raised them.
iv. Rats raised by low-licking mothers exhibit high levels of
methylation regardless of birth mother.
v. Rats raised by high-licking mothers exhibit high levels of
methylation regardless of birth mother.
vi. Rats raised by high-licking mothers exhibit low levels of
methylation regardless of birth mother.
vii. Epigenetic modification of the GR gene is primarily an
inherited trait (i.e. nature)
viii. Epigenetic modification of the GR gene is primarily an
environmentally determined trait (i.e. nurture)
Conclusions considering our understanding of how GR gene
methylation affects rat behavior…
ix. Rats that are born to low-licking mothers are likely to
behave more anxiously than rats born to high-licking mothers.
x. Rats that are raised by low-licking mothers are likely to
behave more anxiously than rats raised to high-licking mothers.
xi. Rats that are born to high-licking mothers are likely to
behave less anxiously than rats born to low-licking mothers.