Review QuestionIs it possible for a male cat to be atortoiseshell?Sex Determination inDrosophila and otherorganismsX chromosome: AutosomeBalanceIn Drosophila, sex is determined by the ratio ofthe number of X chromosomes to the number ofsets of autosomesGenetic sexdeterminationsystems varyOther kinds of sex determination• Grasshoppers, crickets, roaches: XO• Nematodes: ______• Bees, ants, wasps: haplodiploidy• Many Snakes: _______• Lizards: both XX/XY and ZZ/ZW systems• Crocodiles, most turtles, and some lizards, sex isdetermined by the incubation temperature duringa critical period of embryo development. This isknown as ____________________________.Temperature Dependent SexDeterminationIn some animals, sex is not‘determined’ at all!Some fish change sex as they getolder or larger. In clown fish,largest group member is ______,second largest is _______, andall others are ______________.Sometimes the largest fish in thegroup will become ______, allothers will be ______ (wrasses).Coral GobyGobiodon histrioMonogamous pairsIf mate dies orleaves, residentwill__________________________________________.And some species are all femaleCnemidophorus uniparensare all female; reproducevia _________________.Diploid or triploid eggs develop directly from oocytes(___________________), no cellular/nuclear division.At meiosis, identical rather than homologouschromosomes pair, and then segregate.All offspring are females and ______________________________________________________.Cnemidophorus species tend to have extremely lowlevels of genetic diversity.Plants• Hermaphrodite flowers• Hermaphrodite andmale flowers on thesame plant• Male and Femaleflowers on the sameplant• Male and Femaleflowers on differentplantsGenomic ImprintingDifferential expression of alleles at a locus dependingon whether the allele has been inherited from themother or the father.Disease can result from imprintingPaternal SNRPN Gene inactive bymutationPaternal SNRPN gene active--paternally imprinted(chrom. 15)Maternal SNRPN Gene inactive by imprintingFertilizationBoth copiesinactivePrader-WilliSyndromeMild retardationCompulsive eatingObesityDiabetesA nearby gene (also on chrom.15) is maternally imprinted• A mutation in this gene results inAngelman Syndrome: mild retardation,seizures, and involuntary musclecontractions.• Which parent is the mutant allele inheritedfrom in Angelman’s
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