Trigger 9: Epigenetics in action

Question 1

during gametogenesis

Answer 1

epigenetic profile is rest to de novo

Question 2

when genes evade reprogramming

Answer 2

imprinted from previous generations

Question 3

uniparental disomy

Answer 3

people who inherit both homologous chromosomes from the same parents

Question 4

what occurs due to uniparentald disomy

Answer 4

loss of expression of some genes that maternal alleles and increased levels of paternally expressed genes

Question 5

UPD

Answer 5

uniparental disomy

Question 6

UPD was hypothesised to

Answer 6

cause diseases due to changes in epigenotype and disruption of genomic imprinting

Question 7

genomic imprinting

Answer 7

where alleles inherited from one parent are expressed differently to the other parents

• e.g. allele from father is inactive due to imprinting

Question 8

during imprinting the alleles

Answer 8

behave normally in meiosis- only their expression in the offspring is altered

Question 9

during imprinting what is meaningless

Answer 9

dominants- basically hemizygous

Question 10

hemizyoug

Answer 10

. A chromosome in a diploid organism is hemizygous when only one copy is present

Question 11

most common imprinting method

Answer 11

DNA methylation

Question 12

where does de novo emthylase act only at

Answer 12

CpG islands

Question 13

after DNA replication

Answer 13

DNA methylation is replicated DNMT1

Question 14

freshly replicated DNA is methylated only

Answer 14

on one strand (hemi-methylated)

Question 15

maintenance methylase

Answer 15

acts only at hemimethylated CG sites

Question 16

will a change in phenotype occur if the maternal copy of gene is imprinted, but the paternal copy is normal

Answer 16

no

Question 17

will a change in phenotype occur if the maternal copy of gene is imprinted and the paternal copy is mutated

Answer 17

yes

Question 18

function of genomic imprinting

Answer 18

parental conflict theory

Question 19

name two genes involved in the parental conflict theory

Answer 19

IGF2

IFF2R

Question 20

what is the parental conflict theory

Answer 20

imprinting has evolved in mammals because of the conflicting interests of maternal and paternal genes in relation to the transfer of nutrients from the mother to her offspring.

Question 21

interest of mother

Answer 21

to grow well, but leave some resources for me and my future babies

Question 22

interest of mother

Answer 22

grow big and strong

• use all the maternal resources
• future babies may not have my alleles

Question 23

IGF2 and IGF2R in men

Answer 23

IGF2 on

IGF2R off

Question 24

IGF2

Answer 24

insulin-like growth factor

- stimulates foetus to grow

Question 25

IGF2 and IGF2R in female

Answer 25

IGF2 off | IGF2R on

Question 26

IGF2R

Answer 26

insulin-growth factor receptor | - reduces the effect of IGF2

Question 27

in mammals the GF IGF@ interacts with

Answer 27

IGF2R

Question 28

in mice the gens for IGF2 and IGF2R are

Answer 28

both imprinted

Question 29

deleting mother IGF2 receptor genes produces

Answer 29

overly large offspring

Question 30

deleting the fathers IgF2 gene

Answer 30

produces award offspring

Question 31

deleting the mothers IGF2 and fathers IGF2R

Answer 31

produces normally sized offspring

Question 32

imprints on IGF2 and IGF2R usually

Answer 32

cancel each other out

Question 33

changing the imprint on one copy of the gene

Answer 33

has a dramatic effect ton size of offspring

Question 34

example of imprinted genes

Answer 34

liger and tiglons

Question 35

father is lion and mother is tiger

Answer 35

very large

Question 36

father its tiger and mother is lion

Answer 36

normal

Question 37

different imprinted gene between the mother and father cuases

Answer 37

difference in size and appearance between ligers and tigons

Question 38

females have

Answer 38

2 alleles X chromosomes genes

Question 39

males have

Answer 39

1 X chromosome

Question 40

in mammals the early embryo, the paternal X chromosomes (Xp)

Answer 40

is selectively inactivated in all cells

Question 41

how is Xp inactivated

Answer 41

by imprinting

Question 42

when is Xp reactivated

Answer 42

during blastocyst stage

Question 43

Xp or Xm is randomly

Answer 43

inactivated

Question 44

the X that is inactivated

Answer 44

stays silent for subsequentt cell generations