Zanzot Biology Chapter 15

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You perform a testcross using F1 dihybrid flies. If, in the resulting offspring, the percentages of parental and recombinant offspring are about the same, this would indicate that the two genes are
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Duchenne muscular dystrophy is caused by a sex-linked recessive allele. Its victims are almost invariably boys, who usually die before the age of 20. Why is this disorder almost never seen in girls?To express an X-linked recessive allele, a female must have two copies of the allele.What appears to be the mechanism for genomic imprinting?DNA methylation that silences particular genes and DNA methylation that activates particular genesIn an X-linked, or sex-linked, trait, it is the contribution of __________ that determines whether a son will display the trait.the motherT/F a son does not inherit and X from his fathertrueIn X-linked patterns of inheritance,fathers pass X-linked alleles only to their daughters, and mothers pass X-linked alleles to both their daughters and their sonsIn Klinefelter syndrome, individuals are phenotypically male, but have reduced sperm production and may have some breast development in adolescence. The cells of Klinefelter individuals have two X chromosomes and one Y (they are XXY instead of XY). This occurs because of what meiotic error?aneuploidyIn a certain fish, fin rays (supporting structures for the fins) can be either bony or soft in adult fish. Sex linkage in a fish is similar to that in humans. What evidence would most strongly support the idea that the ray locus is on the X chromosome?Matings of soft ray males and bony ray females give different results from the matings of bony ray males and soft ray females.Wild type refers tothe most common phenotype thought to be found in the natural population__________ is the failure of homologous chromosomes to separate in meiosis I or the failure of sister chromatids to separate in meiosis II.nondisjunctionwhat occurs when members of a pair of homologous chromosomes do not move apart properly during meiosis I or when sister chromatids fail to separate during meiosis II?nondisjunctionIn humans, a normal male's somatic cells will have two set(s) of chromosomes and sex chromosomes designated as X and Y, while in bees and ants, a normal male's somatic cells have __________ set of chromosomes, which are; haploidWhy did Morgan choose Drosophila for his genetics experiments?A single mating can produce many offspring and Drosophila chromosomes can be easily distinguishable under a light microscope.Individuals with an extra X chromosomemay have subnormal intelligence or be at risk for learning disabilitiesLinked genesare located near each other on the same chromosomeWith a microscope, you examine some somatic cells from a woman and notice that each nucleus has two Barr bodies. What can you infer about the sex chromosomes in this individual?she is XXXIn werewolves (hypothetically), pointy ears (P) are dominant over round ears (p). The gene is on the X chromosome. (Sex determination in werewolves is the same as for "other" humans.) A certain female werewolf has pointy ears even though her father had round ears. What percentage of her sons will have round ears if she mates with a werewolf with round ears?50%Genomic imprinting in mammals appears to primarily affect genes involved inembryonic developmentGene silencing is calledgenomic imprintingwhat occurs during gamete formation and results in the silencing of a particular allele of certain genesgenomic imprintingThe chromosome theory of inheritance states thatgenes occupy specific positions on chromosomes, homologous chromosomes segregate from each other during meiosis, and chromosomes assort independently during meiosisFemale mammals have two X chromosomes, one from their mother and one from their father. During X inactivation, one X chromosome in each embryonic cell is randomly inactivated; therefore, all of the tissues that arise from that cell have the same inactivated X chromosome. Female mammals are therefore considered to be __________ of the maternal and paternal cells.a mosaicX inactivation occurs when there are at least two X chromosomes present in an individual, forming a structure called a __________ by a random event.Barr bodyDown syndrome is an example of aneuploidy, and the child is __________ for chromosome 21.trisomicQueen Victoria was a carrier of a recessive sex-linked allele for hemophilia. Which of the following possibilities could explain the presence of the hemophilia allele in her genotype?Either her mother was a carrier or her father had hemophilia.Thomas Hunt Morgan worked with what model organism?fruit fliesWhat did Morgan call the phenotype of the organisms before he mutagenized them?wild typeMorgan crossed white eyed males with red eyed females to produce the F1 generation. What progeny did he observe?all red eyed fliesWhen Morgan crossed the red-eyed progeny of the F1 generation, what did he observe?females, all red eyed; males, half red-eyed and half white-eyedT/F. All animals have an XY sex determination schemafalseWhich of the following is not an X-linked recessive trait?Duchenne muscular dystrophy, Red-green colorblindness, Albinism, or HemophiliaalbanismWhat is the recombination frequency of genes on different chromosomes?50%Morgan found that some traits were inherited together more frequently than one would expect due to independent assortment. He attributed this to:linkage between genesAlfred Sturdivant, Morgan's graduate student, reasoned that the closer two genes are on a chromosome, the ________ the expected recombination frequencylowerWhat causes aneuploidy?Non-disjunction of chromosomes in meiosisWhich of the following is not a viable human aneuploid condition? turner syndrome, cri du chat, trisomy 21, klinefelter syndromecri du chat