Unit 3 Exam lecture 20

Question 1

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

Answer 1

epigenetic changes

Question 2

Are epigenetics heritable

Answer 2

yes

Question 3

Explain the process how newly synthesized DNA strands get methylated

Answer 3

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

Question 4

What is Dnmt3

Answer 4

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

Question 5

What silences Dnmt3

Answer 5

royal jelly (siRNAs)

Question 6

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

Answer 6

those bees will become queens

Question 7

royal jelly is an example of

Answer 7

an siRNA

Question 8

What are the three ways that histones can be modified

Answer 8

methylation, acetylation and phosphorylation

Question 9

Modification of histones are carried out by which proteins

Answer 9

polycomb protiens (PcG proteins)

Question 10

PCR2 is what and does what

Answer 10

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

Question 11

What happens when PcGs are mutated

Answer 11

they become non functional causing major developmental changes in phenotype

Question 12

What do PcGs do

Answer 12

proteins which are responsible for the modification of histones

Question 13

What is genomic imprinting

Answer 13

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

Question 14

How can genetic diseases arise around genomic imprinting

Answer 14

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

Question 15

Prada-Willi and Angelman syndroms are exampls of what

Answer 15

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

Question 16

the r1 locus in corn controls what

Answer 16

kernel color

Question 17

Rr allele is for

Answer 17

purple kernels

Question 18

the Rst allele is for

Answer 18

spotted kernels

Question 19

RrRst codes for what colored kernels

Answer 19

spotted kernels

Question 20

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

Answer 20

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

Question 21

What are the three characteristics of paramutation

Answer 21

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

Question 22

Interaction of alleles at b1 locus code for

Answer 22

pigmentation for amount of anthocyanin

Question 23

Epialleles are what

Answer 23

a specific DNA methylation pattern at a given locus

Question 24

B-I B-I gives what color plant

Answer 24

purple

Question 25

B' B' plants give what color plant

Answer 25

green

Question 26

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

Answer 26

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

Question 27

What can B'* do once it has been paramutated

Answer 27

it can now convert B-I alleles

Question 28

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

Answer 28

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

Question 29

Tandem repeats of the B locus in corn act like what

Answer 29

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

Question 30

What converts a B-I to a B'*

Answer 30

siRNAs produced from the tandem repeat of B'

Question 31

What is the kti locus

Answer 31

locus for tyrosine kinase receptor in mice causing pigment

Question 32

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

Answer 32

wild type phenotype of solid color

Question 33

Kit (+) Kit (t) have what phenotype

Answer 33

white feet and tail tip

Question 34

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

Answer 34

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

Question 35

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

Answer 35

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

Question 36

the differences in expression of the glucocorticoid receptors relate to

Answer 36

stress levels

Question 37

changes in what alter expression of glucocorticoid receptors

Answer 37

DNA methylation differences and acetylation of histones

Question 38

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

Answer 38

inhibits binding of transcription factor causing low levels of glucocorticoid effects of this are high stress due to high corticosterone levels

Question 39

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

Answer 39

reduction of deactylase inhibitor allows transcription factor to bind and glococorticoid to be expressed effect of this is low stress due to corticosterone levels

Question 40

Childhood abuse increases chance of adult...

Answer 40

depression, anxiety, suicide

Question 41

Relationship between abuse and what

Answer 41

methylation of glucocortidoid receptors

Question 42

low socioeconomic environment as children alters expression of

Answer 42

over 100 immune genes in adults

Question 43

What is the growth factor that stimulated neuron connections in mice

Answer 43

Bdnf

Question 44

Training. mice to avoid adverse stimulus did what

Answer 44

reduced methylation of Bdnf

Question 45

Demethylated Bdnf causes

Answer 45

more active memory

Question 46

Injecting mice with something inhibiting demethylation had what effect

Answer 46

lower levels of Bdnf and therefore less memory

Question 47

what is the connection found in epigenetics in conjunction with alzheimers

Answer 47

deacetylation of histones

Question 48

Vinclozolin does what and is what

Answer 48

mimics testosteron and binds to androgen receptors it is an endocrine disrupter

Question 49

Was increased or decreased methylation found in vinclozolin treated males

Answer 49

increased DNA methylation

Question 50

Which X is inactivated within a cell is controlled by what

Answer 50

the X inactivation center

Question 51

what is the process of X inactivation

Answer 51

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

Question 52

Jpx does what

Answer 52

stimulates transcription of Xist on inactive X

Question 53

How do you use enzymes to find methylated cytosines

Answer 53

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

Question 54

What is bisulfate sequencing and how does it work

Answer 54

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