武汉大学：《遗传学》课程教学课件（英文讲稿）Chapter 12 Chromosomal Rearrangements and Changes in Chromosome Number

Chapter 12 Chromosomal Rearrangements and Changes in Chromosome Number 14-1

Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 14-1 Chromosomal Rearrangements and Chromosomal Rearrangements and Changes in Chromosome Number Changes in Chromosome Number Chapter 12

Sectionsto study12.1Rearrangements of chromosomalDNA12.2The effects of rearrangements12.3Transposablegeneticelements12.4 Aberrations in chromosome number: Aneuploidy12.5 Variation in number of chromosome sets:Euploidy12.6 Genome reconstructing and evolution14-2

Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 14-2 Sections to study Sections to study 12.1 Rearrangements of chromosomal DNA 12.1 Rearrangements of chromosomal DNA 12.2 The effects of rearrangements 12.2 The effects of rearrangements 12.3 Transposable genetic elements 12.3 Transposable genetic elements 12.4 Aberrations in chromosome number: 12.4 Aberrations in chromosome number: Aneuploidy Aneuploidy 12.5 Variation in number of chromosome sets: 12.5 Variation in number of chromosome sets: Euploidy Euploidy 12.6 Genome reconstructing and evolution 12.6 Genome reconstructing and evolution

Twotypes ofevents that reshapegenomesChromosomal rearrangementsRearrangements of DNA seguences within one or more chromosomes.Changes in chromosome numberLosses orgainsofchromosomes or setsofchromosomes.Significance:Forces thatdrivethe evolution of new speciesChromosome rearrangementGenomeduplication14-3

Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 14-3 Two types of events that reshape genomes  Chromosomal rearrangements Chromosomal rearrangements  Rearrangements of DNA sequences Rearrangements of DNA sequences within one or more chromosomes. within one or more chromosomes.  Changes in chromosome number Changes in chromosome number  Losses or gains of chromosomes or sets of chromosomes. Losses or gains of chromosomes or sets of chromosomes.  Forces that drive the evolution of new species Forces that drive the evolution of new species  Chromosome rearrangement Chromosome rearrangement  Genome duplication Genome duplication Significance:

12.1RearrangementsofchromosomalDNATABLE12.1MajorClasses of ChromosomalRearrangementsLettersrepresentlargechromosomalregions.Different(nonhomologous)chromosomesareindicatedasredandblueNormalRearrangedDeletionCADEIFGHDuplicationABCDEFGHABCBCDEIEICHInversionACBDIEFGH180°rotationTranslocationABCDEFGHLMNOEFGHLIMNIOPQRABCDIPQR14-4

Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 14-4 12.1 Rearrangements of chromosomal DNA

Chromosome breakage and subseguent DNA repair can result inallclassesofchromosomalrearrangements.DDeletionaLossDCB(b)InversionaDeletion(c)CDDuplicationH(d)TranslocationFig12.214-5

Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 14-5 Fig 12.2 Chromosome breakage and subsequent DNA repair can result in Chromosome breakage and subsequent DNA repair can result in all classes of chromosomal rearrangements. all classes of chromosomal rearrangements

AOOAberrant crossingLossover at repeated(a)Dsequences can alsoDeletionproduceDBCArearrangements(b)PInversionDeletion(c)DuplicationH-Translocation(d)DCFig12.3

Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 14-6 Fig 12.3 Aberrant crossing Aberrant crossing￾over at repeated over at repeated sequences can also sequences can also produce produce rearrangements. rearrangements

NormalRearrangedA variety of methods can15335LDDeletionD2522detect chromosomalPCRproductSmallerPCRproductrearrangements3.14.1.3'535'DABOBLDA5Inversion053'Fluorescent in situ322Yhybridization(FISH)PCRproductNoPCRproductsPCRproductprimers1+4primers1+4or2+3primers2+3PCR444.35L5ARODABDDuplication535333NoPCRproductPCRproductA43535ABCDABICH31515326Translocation55.3553EIFGHELFIGDS3362NoPCRproductsprimers2+5or4+6PCRproductPCRproductFig.12.5primers2+5primers 4+6

Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 14-7 A variety of methods can A variety of methods can detect chromosomal detect chromosomal rearrangements rearrangements  Fluorescent Fluorescent in situ hybridization (FISH) hybridization (FISH)  PCR Fig. 12.5

12.2 The effects of rearrangements1. Deletions remove DNA from the genome.(a)DNAbreakagemaycausedeletionsXrays breakbothstrandsABCDEFABFGGofDNADeletionofregionCDE14-8

Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 14-8 1. Deletions remove DNA from the genome. 1. Deletions remove DNA from the genome. 12.2 The effects of rearrangements

Deletions may have phenotypic consequencesHomozygosity for a deletion isoften,but not always,lethal.Heterozygosity for a deletionis often detrimental Evensmall deletions can be harmful.wildtype(twocopiesof Notcht)Haploinsufficiency:Half of thenormal gene dosage does notproduce enough protein productfor a normal phenotype.Vulnerability to mutation thatinactivate the remaining copy ofagene.Forexample,RB-/RB+Dell +(onecopyofNotcht)Fig.12.914-9

Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 14-9 Deletions may have phenotypic consequences Deletions may have phenotypic consequences Fig. 12.9  Homozygosity Homozygosity for a deletion is for a deletion is often, but not always, lethal. often, but not always, lethal.  Heterozygosity Heterozygosity for a deletion for a deletion is often detrimental. Even is often detrimental. Even small deletions can be harmful. small deletions can be harmful.  Haploinsufficiency Haploinsufficiency: Half of the : Half of the normal gene dosage does not normal gene dosage does not produce enough protein product produce enough protein product for a normal phenotype. for a normal phenotype.  Vulnerability to mutation that Vulnerability to mutation that inactivate the remaining copy of inactivate the remaining copy of a gene. For example, a gene. For example, RB /RB+

Deletions in heterozygotes can“uncover"ggenesPseudodominance-A deletion uncovers the phenotype of arecessivemutation.(a)AdeletionuncoversarecessivemutationststDelDeletedregion(b)Deletionscanbeusedtoidentifyagene'slocationGenotypeChromosomesPhenotypestst/stscarletstDeletedregionDel1st/Del1wildtypeDel2st/Del2wildtypeDel3st/Del3scarletDel4st/Del4scarletDel5st/Del5wildtypeFig. 12.614-10

Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 14-10 Deletions in Deletions in heterozygotes heterozygotes can “uncover uncover” genes  Pseudodominance Pseudodominance – A deletion uncovers the phenotype of a A deletion uncovers the phenotype of a recessive mutation. recessive mutation. Fig. 12.6