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Genetics > Exam 3: Epigenetics I > Flashcards

Exam 3: Epigenetics I Flashcards

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Biology 101 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
Q

histone modifications

A

there are more than 100 different post-translational modifications of histone proteins reported

26
Q

histone modifications include (4)

A
  1. methyl groups
  2. acetyl groups
  3. phosphates
  4. ubiquitin
27
Q

DNA methylation is a common epigenetic modification of chromatin at _

A

CpG islands (adding atoms that causes an adjustment of the aa)

28
Q

complexity of the histone code:

A

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
Q

epigenetics include: (2)

A
  1. changes in chromatin structure, which alter gene expression can be inherited
  2. noncoding RNAs
30
Q

types of noncoding RNAs for epigenetic mechanisms (2)

A
  • 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
Q

types of changes in chromatin structure that alter how gene expression can be inherited (2)

A
  1. changes in patterns of DNA methylation

2. chemical modification of histone proteins (methylation or acetylation)

32
Q

multiple biochemical changes modify chromatin structure to _

A

enhance of prevent transcription

33
Q

chromatin can be considered a _ that determines …

A

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
Q

mothers exposing babies to cigarette smoke

A

methylation patterns when babies are exposed to cigarette smoke; significant change in methylation patterns of these babies vs babies not exposed to smoke

35
Q

understanding the language of biochemical modification; the critical concept of the histone code hypothesis is that

A

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
Q

t/f: a huge catalogue of histone modifications have been described, and we have a good functional understanding of most

A

false; we lack a functional understanding of most even with a huge catalogue of described histone modifications

37
Q

the 4 types of chromatin modifying enzymes

A
  1. methyl transferases
  2. demethylases
  3. histone acetyl transferases (HATs)
  4. histone deacetylases (HDAC)
38
Q

methyl transferases

A

adding methyl groups

39
Q

demethylases

A

removing methyl groups; lysine demethylase

40
Q

HATs

A

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
Q

HDACs

A

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
Q

what does it mean by gene “switched on”

A
  • active (open) chromatin
  • unmethylated cytosines
  • acetylated histones
43
Q

what does it mean by gene “switched off”

A
  • silent (condensed) chromatin
  • methylated cytosines
  • deacetylated histones
44
Q

in monogenic disorders such as Rhett syndrome, what affects normal development

A

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
Q

cancer involves many epigenetic lesions that could affect the _ program

A

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
Q

aging involves a loss of the normal _

A

loss of the normal plasticity of response to internal and external environmental signals

47
Q

a common feature of epigenetic lesions in human disease is that they affect the _

A

cell’s ability to change its phenotype

48
Q

the epigenome may modulate the effect of genetic variation either by affecting the _ or _

A

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
Q

the epigenome may, in turn, be affected by

A

sequence variation in the genes encoding chromatin or chaperone proteins

50
Q

environmental factors such as toxins, growth factors, dietary methyl donors, and hormones can affect the

A

genome and the epigenome

51
Q

a type of dietary methyl donor

A

folic acid; low folate = inappropriate epigenetic regulation of the babies genome

52
Q

DNA methylation is stably maintained through

A

DNA replication (mitosis)

53
Q

DNA methylation: the parent DNA strand promotes

A

modification of the newly synthesized strand to maintain methylation status

54
Q

DNA methylation: CpG islands =

A

CG on old strand

GC on new strand

55
Q

t/f: queen and worker bees are genetically identical

A

true; epigenetic changes are responsible for differences in the phenotypes (royal jelly causes silencing of a methyl transferase gene)

56
Q

examples of epigenetic effects by RNA molecules (2)

A
  1. paramutation

2. X inactivation (by Xist)

57
Q

what is paramutation

A

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
Q

paramutation in mice

A

microRNA that targets and degrades the Kit mRNA

59
Q

what happens in X inactivation

A

the Xist gene on the inactive X produces a long noncoding RNA that coats the inactive X chromosome and suppresses transcription

60
Q

several genes w/in the X-inactivation center interact to bring about inactivation of one X chromosome while

A

keeping the other X chromosome active

Genetics (37 decks)

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