Unit 3 Exam lecture 20 Flashcards

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1
Q

Phenotypes and processes transmitted to cells but not the result of genome sequence are called

A

epigenetic changes

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2
Q

Are epigenetics heritable

A

yes

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3
Q

Explain the process how newly synthesized DNA strands get methylated

A

After replication, half of double strand is methylated and half is unmethylated, methyl transferases add methyl groups to unmethylated strands

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4
Q

What is Dnmt3

A

active gene in female honey bees that stimulates methylation of genes for queen characteristics

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5
Q

What silences Dnmt3

A

royal jelly (siRNAs)

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6
Q

What happens early in development if a worker bee female is injected with siRNA that targets Dnmt3

A

those bees will become queens

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7
Q

royal jelly is an example of

A

an siRNA

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8
Q

What are the three ways that histones can be modified

A

methylation, acetylation and phosphorylation

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9
Q

Modification of histones are carried out by which proteins

A

polycomb protiens (PcG proteins)

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10
Q

PCR2 is what and does what

A

it is a PcG protein that adds two methyl groups to lysine 27 of H3

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11
Q

What happens when PcGs are mutated

A

they become non functional causing major developmental changes in phenotype

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12
Q

What do PcGs do

A

proteins which are responsible for the modification of histones

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13
Q

What is genomic imprinting

A

when one copy of a gene or group of genes is switched off

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14
Q

How can genetic diseases arise around genomic imprinting

A

One copy of a gene is silenced and the other active, if the active copy gets deleted then it can cause a genetic disease

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15
Q

Prada-Willi and Angelman syndroms are exampls of what

A

Genetic diseases due to deletion of non genomic imprinted copy of gene

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16
Q

the r1 locus in corn controls what

A

kernel color

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17
Q

Rr allele is for

A

purple kernels

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18
Q

the Rst allele is for

A

spotted kernels

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19
Q

RrRst codes for what colored kernels

A

spotted kernels

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20
Q

Subsequent Rr plants after being RrRst will produce which kernels and why

A

spotted kernels due to interaction of alleles that lead to heritable change in the Rr allele

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21
Q

What are the three characteristics of paramutation

A
  1. newly stablished expression pattern is transmitted to future generation even though the original allele is absent
  2. altered allele is now able to convert other alleles to new phenotype
  3. no associated DNA sequence different in altered alleles
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22
Q

Interaction of alleles at b1 locus code for

A

pigmentation for amount of anthocyanin

23
Q

Epialleles are what

A

a specific DNA methylation pattern at a given locus

24
Q

B-I B-I gives what color plant

A

purple

25
Q

B’ B’ plants give what color plant

A

green

26
Q

Crossing a B-I B-I and a B’ B’ gives what genotype plant

A

B-I B’ but then a paramutation occurs where the B’ changes the B-I into a B’*

27
Q

What can B’* do once it has been paramutated

A

it can now convert B-I alleles

28
Q

What are the differences between the B-I and B’ genes

A

both have tandem repeats upstream of the protein coding sequence however B’ genes express the epiallele of a highly methylated tandem repeat region

29
Q

Tandem repeats of the B locus in corn act like what

A

enhancer sequences, if unmethylated then greater expression of pigment and if methylated less expression of pigment

30
Q

What converts a B-I to a B’*

A

siRNAs produced from the tandem repeat of B’

31
Q

What is the kti locus

A

locus for tyrosine kinase receptor in mice causing pigment

32
Q

Kit(+) Kit (+) mice have what phenotype

A

wild type phenotype of solid color

33
Q

Kit (+) Kit (t) have what phenotype

A

white feet and tail tip

34
Q

The kit locus is an example of what in mice, how is it an example of this

A

paramutation because when crossing a Kit (+) Kit (+) with a Kit (+) Kit (t),

half of the genotypes will be Kit (+) Kit (+) and half the genotypes will be Kit (+) Kit (t)

however half of the Kit (+) Kit (+) mice will have the wild type phenotype and half will have the Kit (+) Kit (t) phenotype

35
Q

Why do mice that may have the Kit (+) Kit (+) genotype express the phenotype of Kit (+) Kit (t)

A

miRNAs that degrade Kit mRNA passed on from parent to some progeny (Kit* allele passed on)

36
Q

the differences in expression of the glucocorticoid receptors relate to

A

stress levels

37
Q

changes in what alter expression of glucocorticoid receptors

A

DNA methylation differences and acetylation of histones

38
Q

Methylation of DNA has what effect in mice relating to behavioral epigenetics

A

inhibits binding of transcription factor causing low levels of glucocorticoid

effects of this are high stress due to high corticosterone levels

39
Q

Acetylation of histones has the effect in mice relating to behavioral epigenetics

A

reduction of deactylase inhibitor allows transcription factor to bind and glococorticoid to be expressed

effect of this is low stress due to corticosterone levels

40
Q

Childhood abuse increases chance of adult…

A

depression, anxiety, suicide

41
Q

Relationship between abuse and what

A

methylation of glucocortidoid receptors

42
Q

low socioeconomic environment as children alters expression of

A

over 100 immune genes in adults

43
Q

What is the growth factor that stimulated neuron connections in mice

A

Bdnf

44
Q

Training. mice to avoid adverse stimulus did what

A

reduced methylation of Bdnf

45
Q

Demethylated Bdnf causes

A

more active memory

46
Q

Injecting mice with something inhibiting demethylation had what effect

A

lower levels of Bdnf and therefore less memory

47
Q

what is the connection found in epigenetics in conjunction with alzheimers

A

deacetylation of histones

48
Q

Vinclozolin does what and is what

A

mimics testosteron and binds to androgen receptors

it is an endocrine disrupter

49
Q

Was increased or decreased methylation found in vinclozolin treated males

A

increased DNA methylation

50
Q

Which X is inactivated within a cell is controlled by what

A

the X inactivation center

51
Q

what is the process of X inactivation

A
  1. Tsix transcriped on active X
  2. Xist gets transcribed on silenced X
  3. Formation of lncRNA which coats the Xi but not Xa
  4. Xist RNA recruits PCR2 which produces histone modifications on Xi via methylation
52
Q

Jpx does what

A

stimulates transcription of Xist on inactive X

53
Q

How do you use enzymes to find methylated cytosines

A

use restruction enzymes HPAII and MSPI which cut the same CCGG cut site but HPAII will not cleave if one of the cytosines is methylated

compare results to find methylation patterns

54
Q

What is bisulfate sequencing and how does it work

A

another way to study expression of cytosine methylation

exposure to bisulfate will convert unmethylated cytosine to uracil,
when you sequence will now register as a T
Methylated cytosine will stay the same