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Genetics > Exam 3: Epigenetics I > Flashcards

Exam 3: Epigenetics I Flashcards

1
Q

during the process of development, a genotype is transduced to produce a _

A

phenotype eg more than 200 cell types

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2
Q

“epigenesis”

A

how an embryo develops

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3
Q

“genetics”

A

study of genes and heredity

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4
Q

epigenetics is “_” change in…

A

“heritable” change in phenotype that does not involve changes in the DNA sequence

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5
Q

behavioral epigenetics

A

life experiences, esp early in life, have long-lasting effects on behavior

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6
Q

epigenetic changes induced by _ behavior

A

maternal behavior

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7
Q

epigenetic effects of early _ in humans

A

stress

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8
Q

t/f: epigenetics in cognition

A

true

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9
Q

crop abundance and failure (nutritional status) can have health effects that persist for several generations. thus, _ are passed to offspring. what does this remind you of?

A

acquired traits; epigenetics

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10
Q

paternal grandpa’s food supply just before pubertal growth spurt is inversely associated with longevity of grandchildren. how does this look in low and high food supply

A 
low= grandpa low food supply means grandchildren have longer longevity (reduced CV mortality)
high= grandpa high food supply means grandchildren have low longevity (diabetes mortality)
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11
Q

the thrifty phenotype theory proposes:

A

when environment is poor for a parent, there is this internal mechanism that calculates environment will be poor for offspring. biochemical modifications allow pre-adaptation to produce offspring metabolically thrifty to efficiently store calories

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12
Q

what will be the effect in an environment which is more plentiful and the thrift phenotype theory is in effect?

A

if environment is plentiful, the thrifty phenotype is no longer advantageous as the child would have a difficult time losing weight; adverse fetal environment followed by plentiful food in adulthood may be a recipe for adult chronic disease

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13
Q

smoking while pregnant affects grandkids, even when mothers did not smoke

A

increases risk of asthma; measured methylation at 26 CpG loci and these DNA methylation changes appear to be tobacco-specific. children with grandmas who smoke have an incr risk of asthma even when their mothers did not smoke

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14
Q

epigenetics and stress

A

not just telomeres affected by stress. epigenetic modifications due to stress can be incorporated into our genomes; and possibly passed on to the next generation

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15
Q

young rats exposed to more licking and grooming from their mothers develop different patterns of _, which alters the expression of _

A

different patterns of DNA methylation, which alters the expression of stress-response genes and makes them less fearful as adults

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16
Q

changes in chromatin structure, which alters _

A

gene expression

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17
Q

molecular mechanisms that alter chromatin structure: (3)

A
  1. changes in patterns of DNA methylation
  2. chemical modification of histone proteins
  3. RNA molecules that affect chromatin structure and gene expression
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18
Q

DNA methylation =

A

addition of methyl groups to nucleotide bases

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19
Q

most common of DNA methylation

A

methylation of cytosine to produce 5-methylcytosine in CpG Islands (usu promoter seqs)

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20
Q

generally, methylated cytosines are associated with

A

gene repression and chromatin condensation

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21
Q

acetylated histones

A

generally, acetylated histones are associated w/ gene activity and open chromatin structure

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22
Q

methylated histones

A

methylated histones (usu a lysine) are associated w/ variable gene activity depending of which lysine is methylated

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23
Q

H3K4me1 mean

A

histone 3, lysine 4, one methyl group was added to lysine 4

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24
Q

H3K27ac mean

A

histone 3, lysine 27 acetylated

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25
histone modifications
there are more than 100 different post-translational modifications of histone proteins reported
26
histone modifications include (4)
1. methyl groups 2. acetyl groups 3. phosphates 4. ubiquitin
27
DNA methylation is a common epigenetic modification of chromatin at _
CpG islands (adding atoms that causes an adjustment of the aa)
28
complexity of the histone code:
H3 has 19 diff lysines that can be methylated (0-3 methyl atoms added) calculates to be 4^19=280 billion patterns of lysine methylation possible on H3; we see how important variation is as cells can take advantage of this to subtly modify gene expression
29
epigenetics include: (2)
1. changes in chromatin structure, which alter gene expression can be inherited 2. noncoding RNAs
30
types of noncoding RNAs for epigenetic mechanisms (2)
- microRNAs - long noncoding RNAs * tools that cell use to change amt of protein that gets made thus affecting gene expression w/o changing nucleotide seq of promoter of that gene or aa seq itself*
31
types of changes in chromatin structure that alter how gene expression can be inherited (2)
1. changes in patterns of DNA methylation | 2. chemical modification of histone proteins (methylation or acetylation)
32
multiple biochemical changes modify chromatin structure to _
enhance of prevent transcription
33
chromatin can be considered a _ that determines ...
a developmental cell type-specific filter of genomic seq information that determines which genes are transcribed into RNA *language; categorizing the biochemical changes that are assoc with changes in gene expression and cell phenotype*
34
mothers exposing babies to cigarette smoke
methylation patterns when babies are exposed to cigarette smoke; significant change in methylation patterns of these babies vs babies not exposed to smoke
35
understanding the language of biochemical modification; the critical concept of the histone code hypothesis is that
the histone modifications serve to recruit other proteins by specific recognition of the modified histone via protein domains specialized for such purposes *work together to produce a reliable and reproducible pattern of expression during development*
36
t/f: a huge catalogue of histone modifications have been described, and we have a good functional understanding of most
false; we lack a functional understanding of most even with a huge catalogue of described histone modifications
37
the 4 types of chromatin modifying enzymes
1. methyl transferases 2. demethylases 3. histone acetyl transferases (HATs) 4. histone deacetylases (HDAC)
38
methyl transferases
adding methyl groups
39
demethylases
removing methyl groups; lysine demethylase
40
HATs
adding acetyl group(s); acetylate conserved lysine aas on histone proteins. lysine acetylation of histones modifies binding sites for specific protein-protein interaction domains
41
HDACs
enzyme that removes acetyl group(s) from lysine aas on a histone, allowing the histones to wrap the DNA more tightly, generally resulting in inhibition of transcription
42
what does it mean by gene "switched on"
- active (open) chromatin - unmethylated cytosines - acetylated histones
43
what does it mean by gene "switched off"
- silent (condensed) chromatin - methylated cytosines - deacetylated histones
44
in monogenic disorders such as Rhett syndrome, what affects normal development
a defect in the normal epigenetic apparatus itself (in Rhett, the defect is in the protein that recognizes methyl groups and genes are not adequately silenced)
45
cancer involves many epigenetic lesions that could affect the _ program
pluripotent program (cancer has all kinds of epigenetic modifications that help produce a gene expression pattern that helps improve the cells ability to avoid detection and promote uncontrolled growth)
46
aging involves a loss of the normal _
loss of the normal plasticity of response to internal and external environmental signals
47
a common feature of epigenetic lesions in human disease is that they affect the _
cell's ability to change its phenotype
48
the epigenome may modulate the effect of genetic variation either by affecting the _ or _
gene's expression through the action of chromatin proteins or DNA methylation OR by modulating protein folding of the gene product of the variant locus or chromatin protein
49
the epigenome may, in turn, be affected by
sequence variation in the genes encoding chromatin or chaperone proteins
50
environmental factors such as toxins, growth factors, dietary methyl donors, and hormones can affect the
genome and the epigenome
51
a type of dietary methyl donor
folic acid; low folate = inappropriate epigenetic regulation of the babies genome
52
DNA methylation is stably maintained through
DNA replication (mitosis)
53
DNA methylation: the parent DNA strand promotes
modification of the newly synthesized strand to maintain methylation status
54
DNA methylation: CpG islands =
CG on old strand | GC on new strand
55
t/f: queen and worker bees are genetically identical
true; epigenetic changes are responsible for differences in the phenotypes (royal jelly causes silencing of a methyl transferase gene)
56
examples of epigenetic effects by RNA molecules (2)
1. paramutation | 2. X inactivation (by Xist)
57
what is paramutation
an interaction btwn 2 alleles that leads to a heritable change in expression of one of the alleles w/o changing the sequence (in corn and in mice)
58
paramutation in mice
microRNA that targets and degrades the Kit mRNA
59
what happens in X inactivation
the Xist gene on the inactive X produces a long noncoding RNA that coats the inactive X chromosome and suppresses transcription
60
several genes w/in the X-inactivation center interact to bring about inactivation of one X chromosome while
keeping the other X chromosome active

Genetics (37 decks)

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