Imprinting Flashcards

Question

Imprinting pattern in cells

Answer 1

Pattern in all cells in body is the same until go to gameteogensis

Answer 2

Methylated if maternally imprinted genes in female Methylate if paternally imprinted gene in males Image -- A1 and A2 = imrpinted because that gene is maternally imprint = imprint in ALL egg even in the A2 alelle from Paternal

Answer 3

Answer: Oogensis

Answer 4

Oogensis = ALL egg get maternal imprinting pattern Spermogensis = ALL Sperm get paternal imprinting pattern

Answer 5

All of the gametes form an indiviuals receive the same imprinting pattern The pattern depends on the sec of the person creating the gametes All members of the same sex produce the same imprinting patterns Imprinting is indepentdent of the alleles

Answer 6

NOT all genes are imprinted Only 1% of mammales and flowering plants

Answer 7

Genomic imprinting has been identified in mammals + insects + flowering plants 1% of mammalian genes are imprinted

Answer 8

Answer: Larger than normal IGF2 -- have mom + dad Receptor -- have mom GF > Receptor = larger

Answer 9

Tiger = have 2 GF and 2 Receptor; Lion 1:1 Paternal lion receptor = off Have GF (from Tiger) + R (from toger) + GF (from lion but no receptor) = GF > Recptor = larger

Answer 10

Parental conflict dad = wants to put all resources in kids to grow big and strong = use all maternal resources --> turn off receptor = have more GF hormone than receptor Mom = Wants kids to grow big enough to be healthy BUT leave some resources for mom and future kids = turn off hormone and turn receptor on

Answer 11

1. Prader Willi 2. Angelman's syndorme

Answer 12

Maternally Imprinted --> rely on expression of paternal - Occurs when have problems with paternal PW genes

Answer 13

Linked to the same imprinted region on Chromsome 15 Some silence in egg = maternally imprinted Some silence in sperm= paternally imprinted

Answer 14

Imprinting is required for normal development Individuals normally have one active copy of imprinted gene If have improper imprinting = leads to individual with 2 active copies or 2 inactive copies = develop abnormalities or cancer

Answer 15

Patenrally imprinted = Transcript is silenced from paternal allele --> caused when have probelms with maternal Angelman genes

Answer 16

A common cause of PWS and AS is a de novo delation of a region of Chromosome 15 that removes both the PW genes and teh AS genes - Mutation occurs during gamnetogensis Delection occurs in oogensis --> PW genes are fine because have paternal; chrosmome BUT the genes for Angelman are off on the paternal and rely on the maternal = gene is missing if have deltion in oogensis = result of deltion is Angleman Deletion in Spermogensis = Angelman genes are fine (expressed on maternal) BUT PW are silenced in maternal and paternal are missing = get PW syndrome Inheritance of the same deletion can lead to different disease depending on the parent or origin

Answer 17

Answer: Angelman -- because get Angleman genes from neither Paternally imprinted = Methylated/off in paternal

Answer 18

Answer: Prader Willi No PW gene (methylaed/off in mom and deleted in dad) = get PW ***Lack of gene = get syndorme

Answer 19

In generation 1 - Know one A1 is methylated in mom because got one allele from mom that must be methylated - Know A1 is methylated in dad because he has the trait = express A2 = A1 is methylated

Answer 20

Overall: Parental Conflict Males want offspring tp use all maternal resources to get as big as possible (not interested in long term success of partner because can always find another partner) - Accomplish their goals by passing an active copy of Growth factor and turn off receptor -- receptor nuetralizes the effect of growth factor Females have a vested interest in having healthy kids but they want children to leave some resources for them and future kids - Accomplish goals by turning off growth hormone (GF is imprinted and recptor is on) IGF2 GF is maternally imprinted Receptor = Paternally imprinted In combination = monoalleleic expression of both genes --> 1:1 ratio

Answer 21

In combination of both parents = mono-allelic expression of both genes -

Answer 22

Under most circumstances IGF2 is maternally imprinted and receptor is paternally imprinted = 1:1 expression ratio of the hormone and receptor - When have equal expression = get normal size individuals - GF > recptor = get larger size - GF < Receptor = get smaller size

Answer 23

NO imprinting patters are not necessarily conserved between all animals Example: Tigers = do not imprint GF or receptor Lions = Maternally imprint GF and paternally imprint recepyor Female Tiger + Male lion = Make liger - Female tiger = privides gametes with both GF and recprtor on and lion gives gametes where GF is turned on and the receptor is off END = 2 copies of GF and 1 copy of receptor = GF > recptor = larger

Answer 24

Means that there is no backup allele = imprinted genes are particularly sensitive to envirnmental stress - Additional epigentic modifications may reduce gene expression leading to phenotyoe - Envirnmnetal stessed

Answer 25

Environmental stressors are known to interfere with DNA methyltransferases involved in imprinting process

Answer 26

Example: Have carrier mom in generation 1 (mom = AA') - Know mom is carrier - so if A' is what leads to trait themn A' must be silenced because she does not have the trait - Mom passes A' allels to her son and her second dauhter - because both are carriers but not expressing the trait = know they have to be silenced copy of the alelle Carrier son in genertion has a son that is affected - Son must have inherited the A' alelle leading to the trait and that allele must be expressed - Carrier daughter in second generation that doesn't have the trait has 2 children that are carriers --> these children muct have inherited the same A' alelle and teh A' must be silenced or they would have phenotype Overall: have a female that passes down silenced copies of A' and her daughter also passes silenced copies = consistent with maternal imprinting AND son who is carrier who does not imrpint allele so wehn pass down allele it is expressed

Answer 27

Mendelian Ratios should apply Example - Mom AA' --> Should gives A to 1/2 offspring and A' to 1/2 offspring -- get 50% A and 50% A'

Answer 28

Paternal Imprinting Have a carrier male in genration 1 (A') -- A' must be methylated --> passed A' to two offspring and each are Methylated The son in generation 2 passes down A' to one of his offspring --> offspring is also affected = the offspring inherite methylated Carrier daughter in genration 2 passes A' allele in mendelian ratios to her offspring --> because this is paternally imprinted the A' allele passed on by female is not imprinted = active = both offspring in genration 3 are affected

Answer 29

Have an affected female with A' allele that leads to phenotype -- she expresses phenotype = know A' is active in ger = her copy of A must be methylated; patner is AA (one copy is methylated) Have 4 kids -- mendelian ratios apply - Affected female passes A' to 2 offpsirng and passes A top 2 offspring --> because maternally imprinted gene = all alles that she passes down is methylated and silenced ( A and A' she passes down - all silenced) Offspring in generation 2 have a silenced copy of maternally inherited allele - even though have A' its is silenced - A' in second generation will be phenotypically normal because methylaed = carriers - Father in generation one - passes A to all offspring - because maternally imprinted he will pass down active copies of A In generation 3: - carrier female pass her A' allele to half of her offspring and her WT A to half of offspring - Maternally imprinted alelle = she will sielnce each copy of alelele that she passes down - 1/2 offspring have A' -- they are both silenced = carriers - All 4 children will be normal while 2 carriers - carrier male in generation 2 gives A' alelle to 1/2 of his offspring and A to other half --> maternally imprinted alelle so all of his contrubition remain active; his Wt partner gives A allele that will be silenced because maternally imprinted -- offspring that inherit A' alelele = express diases alelle = diseased - Other two offspring are phenotyoically WT and genotypically WT - female AA pass down impronted copyt of A to each offspring -- partner will pass down active A locus - Wt male offspring will pass down Active A alelles while his partner will pass down imrointed copy of her allele ***For maternaly imrpinted genes -- feamkes always pass down silencec copies of alelles wheras males will pass down activce copies of alelles

Answer 30

Patenrally imrpted green A = silenced in the next generation A and A’ alleles that are inherited in Generation 2 = active - Indiviual with A’ express disease phenotype Patenral imprinting means that the males will pass down silences cpopies of their alleles to their offspring Indiviuals with A’ allele from mom = express disease phenotyoe Offspring that get A’ allele =from affected foather have a silenced opy of diseased allele = they will be cacriers

Answer 31

Imprinting genes are those that are silenced (methylated) during gametogensis Imrpinting patterns are specific to oofgenesis/spermogensis Imprints are earased then re-established during gametogenesis Imrpinting leads to monoalleleic expression Imrpinted genes are senistive to envirnmental modifications Imrpting may be the result of gentic conflict between female and male