Genomic imprintingHuman imprinted gene databasewhich statements regarding nucleoid structure of mitochondria and chloroplasts are true?

Genetic Imprinting - National Human Genome Research Institute

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In genomic imprinting the ability of a gene to be expressed depends upon the sex of the parent who passed on the gene. In some cases imprinted genes are ... Skiptomaincontent ​GeneticImprinting = Ingenomicimprintingtheabilityofagenetobeexpresseddependsuponthesexoftheparentwhopassedonthegene.Insomecasesimprintedgenesareexpressedwhentheareinheritedfromthemother.inothercasestheyareexpressedwheninheritedfromthefather.Unlikegenomicmutationsthatcanaffecttheabilityofinheritedgenestobeexpressed,genomicimprintingdoesnotaffecttheDNAsequenceitself.GenomicimprintingaffectsgeneexpressionbychemicallymodifyingDNAand/oralteringthechromatinstructure.Often,genomicimprintingresultsinagenebeingexpressedonlyinthechromosomeinheritedfromoneortheotherparent.Whilethisisanormalprocess,whencombinedwithgenomicmutations,diseasecanresult.Forexample,Prader-WillisyndromeandAngelmansyndromearetwodistinctdiseasescausedbyadeletioninthesamepartofchromosome15.Whenthisdeletionoccursonthechromosome15thatcamefromthefather,thechildwillhavePrader-Willisyndrome.However,whenthedeletionoccursonthechromosome15thatcamefromthemother,thechildwilldevelopAngelmansyndrome.Thisoccursbecausegeneslocatedinthisregionundergogenomicimprinting. Narration Geneticimprintingisarathermysteriousphenomenonwhichhasbecomesomewhatbetterunderstoodinthelastfewyears.Essentially,whatitreferstoisthechemicalmodificationofaDNAsequence.KeepinmindherethattheDNAsequenceitselfisnotchanging.ThesearemodificationstotheDNAsequenceitselfthatoccurinacell--usuallyreferstoagermcell,eitheraneggcelloraspermcell--andthatchangeispassedonfromonegenerationtoanother.Thereasonitconfusedscientistsformanyyearsisthatitisanon-sequenced-basedmechanismofinheritance.Initially,itwasthoughtthatallinheritanceisbasedonchangesinsequence;thisturnsoutnottobetrue.Inoneofthosemechanisms,whichisnotinvolvedinchangeofsequence,butratheraninheritedchemicalchangetoaDNAsequence,isreferredtoasimprinting.Andthatimprinting,thereasonit'simportantisthatchemicalmodification,whichispassedonfromthemotherorthefathertotheoffspring,changesthefunctionofthegeneorthegeneproduct,whetherit'sexpressionoractuallythefunctionofthegeneproductitself. ChristopherP.Austin,M.D. RelatedTerms DeoxyribonucleicAcid(DNA) Epistasis Gene GeneExpression GeneRegulation Histone Protein BrowseTerms A B C D E F G H I J K L M N O P Q R S T U V W X Y Z FeaturedContent IntroductiontoGenomics PolygenicRiskScores

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