Concepts of Genetics (12th Edition)
12th Edition
ISBN: 9780134604718
Author: William S. Klug, Michael R. Cummings, Charlotte A. Spencer, Michael A. Palladino, Darrell Killian
Publisher: PEARSON
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Chapter 7, Problem 24ESP
In the wasp Bracon hebetor, a form of parthenogenesis (the development of unfertilized eggs into progeny) resulting in haploid organisms is not uncommon. All haploids are males. When offspring arise from fertilization, females almost invariably result. P. W. Whiting has shown that an X-linked gene with nine multiple alleles (Xa, Xb, etc.) controls sex determination. Any homozygous or hemizygous condition results in males, and any heterozygous condition results in females. If an Xa/Xb female mates with an Xa male and lays 50 percent fertilized and 50 percent unfertilized eggs, what proportion of male and female offspring will result?
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Butterflies have an X-Y sex-determination system that is different from that of flies or humans. Female butterflies may be either XY or X0, while butterflies with two or more X chromosomes are males. This photograph shows a tiger swallowtail gynandromorph, which is half male (left side) and half female (right side). Given that the first division of the zygote divides the embryo into the future right and left halves of the butterfly, propose a hypothesis that explains how nondisjunction during the first mitosis might have produced this unusual-looking butterfly.
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Female flies with white eyes and miniature wings (both X-linkedrecessive traits) were crossed to male flies with red eyes and longwings. On rare occasions, female offspring were produced withwhite eyes. If we assume these females are due to errors in meiosis, what would be the most likely chromosomal composition ofsuch flies? What would be their wing length?
Barr bodies are formed to adjust X chromosome dosage in species other than humans, such as Drosophila (fruit flies) and C. elegans (nematodes). True or False ?
Chapter 7 Solutions
Concepts of Genetics (12th Edition)
Ch. 7 - Campomelic dysplasia (CMD1) is a congenital human...Ch. 7 - Carbon Copy (CC), the first car produced from a...Ch. 7 - Gender is someones conscious and unconscious...Ch. 7 - Gender is someones conscious and unconscious...Ch. 7 - HOW DO WE KNOW? In this chapter, we have focused...Ch. 7 - Review the Chapter Concepts list on p. 151. These...Ch. 7 - Distinguish between the concepts of sexual...Ch. 7 - Contrast the XX/XY and XX/X0 modes of sex...Ch. 7 - Describe the major difference between sex...Ch. 7 - How do mammals, including humans, solve the dosage...
Ch. 7 - The phenotype of an early-stage human embryo is...Ch. 7 - What specific observations (evidence) support the...Ch. 7 - Describe how nondisjunction in human female...Ch. 7 - An insect species is discovered in which the...Ch. 7 - When cows have twin calves of unlike sex...Ch. 7 - An attached-X female fly, XXY (see the Insights...Ch. 7 - Assume that on rare occasions the attached X...Ch. 7 - It has been suggested that any male-determining...Ch. 7 - What is a Barr body, and where is it found in a...Ch. 7 - Indicate the expected number of Barr bodies in...Ch. 7 - Define the Lyon hypothesis.Ch. 7 - Can the Lyon hypothesis be tested in a human...Ch. 7 - Predict the potential effect of the Lyon...Ch. 7 - Cat breeders are aware that kittens expressing the...Ch. 7 - In mice, the Sry gene (see Section 7.2) is located...Ch. 7 - The genes encoding the red-and...Ch. 7 - What is the role of the enzyme aromatase in sexual...Ch. 7 - In the wasp Bracon hebetor, a form of...Ch. 7 - The Amami spiny rat (Tokudaia osimensis) lacks a Y...Ch. 7 - In mice, the X-linked dominant mutation Testicular...Ch. 7 - When the cloned cat Carbon Copy (CC) was born (see...Ch. 7 - In reptiles, sex determination was thought to be...Ch. 7 - In chickens, a key gene involved in sex...
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- Males of many diploid species (like us) have X and Y sex chromosomes. They are hemizygous for most X- linked genes. Thus, males express most X-linked alleles, whether they are dominant or recessive in females. In the fruit fly Drosophila, it is common to achieve the equivalent of a test cross of X-linked genes in females by assessing the readily observed phenotypes of their male progeny. Since males do not receive X-linked genes from their father, sires of these crosses can be normal or wild-type flies. In fly genetics, it is conventional to name a gene after the mutant phenotype that enabled its discovery. Your challenge is to establish gene order and map distances between three X-linked genes in Drosophila. Each gene is represented by recessive mutant alleles that express rather distinctive phenotypes relative to their dominant wild-type alternative alleles. Flies expressing fruitless (f) are bisexual, lush (1) have a heightened responses to ethanol, and ken&barbie (kb) lack external…arrow_forwardIn C. elegans, lon-2 and unc-2 are recessive mutations that are 8 map units apart on the X chromosome. An hermaphrodite who is Lon and Unc is mated to a wild-type male. An F1 hermaphrodite is mated to a wild-type male. What are the expected percentages of the different phenotypes among the male progeny?arrow_forwardThe picture below represents a G1 cell from a newly discovered species that uses the X/Y sex determination system. Alleles for the different autosomal genes of interest are indicated on the chromosomes, and genes R and T are 36 cM apart. Red lines show maternal chromosomes, and blue lines show paternal chromosomes. Answer the following questions about this individual. a) This individual can produce a pool of different gametes. List any TWO potential gametes that will occur at different frequencies. Give the alleles of each gamete contained within a set of brackets, and indicate the expected frequency (up to two decimals) at which that gamete would occur. b) Name any two loci in this individual that can result in recombination in the gametes via the process of independent assortment. c) What is the sex of this individual? Justify your answer. d) Give the term that will describe the morphology of the chromosome that carries the R/T alleles. e) Provide the genotype of the fertilizing male…arrow_forward
- The picture below represents a G1 cell from a newly discovered species that uses the X/Y sex determination system. Alleles for the different autosomal genes of interest are indicated on the chromosomes, and genes R and T are 16 cM apart. Red lines show maternal chromosomes, and blue lines show paternal chromosomes. Answer the following questions about this individual.d) Provide the genotype of the fertilizing male gamete that produced this individual. e) This individual can produce a pool of different gametes. List any TWO potential gametes that will occur at different frequencies. Give the alleles of each gamete contained within a set of brackets, and indicate the expected frequency (up to two decimals) at which that gamete would occur.arrow_forwardThe picture below represents a G1 cell from a newly discovered species that uses the X/Y sex determination system. Alleles for the different autosomal genes of interest are indicated on the chromosomes, and genes R and T are 36 cM apart. Red lines show maternal chromosomes, and blue lines show paternal chromosomes. Answer the following questions about this individual. g|G a) This individual can produce a pool of different gametes. List any TWO potential gametes that will occur at different frequencies. Give the alleles of each gamete contained within a set of brackets, and indicate the expected frequency (up to two decimals) at which that gamete would occur. b) Name any two loci in this individual that can result in recombination in the gametes via the process of independent assortment. c) What is the sex of this individual? Justify your answer. d) Give the term that will describe the morphology of the chromosome that carries the R/T alleles. e) Provide the genotype of the fertilizing…arrow_forwardLet’s suppose that two different X-linked genes exist in mice,designated with the letters N and L. Gene N exists in a dominant,normal allele and in a recessive allele, n, that is lethal. Similarly,gene L exists in a dominant, normal allele and in a recessive allele,l, that is lethal. Heterozygous females are normal, but males thatcarry either recessive allele are born dead. Explain whether or notit would be possible to map the distance between these two genesby making crosses and analyzing the number of living and deadoffspring. You may assume that you have strains of mice in whichfemales are heterozygous for one or both genes.arrow_forward
- In organisms with the ZZ-ZW sex-determining system, from which of the following possibilities can a female inherit her Z chromosome? Yes No Her mother's mother Her mother's father Her father's mother Her father's fatherarrow_forwardIn elegans, lon-2 and unc-2 are recessive mutations that are 8 map units apart on the X chromosome. An hermaphrodite who is Lon and Unc is mated to a wild-type male. An F1 hermaphrodite is mated to a wild-type male. What are the expected percentages of the different recombinant phenotypes among the male progeny?arrow_forwardA human disease known as vitamin D–resistant rickets isinherited as an X-linked dominant trait. If a male with thedisease produces children with a female who does not have thedisease, what is the expected ratio of affected and unaffectedoffspring?arrow_forward
- Because of non-disjunction in some stocks of Drosophila. melanogaster, about 1 in 65,000 egg cells have two copies of the X chromosome and about 1 in 375 egg cells have no X chromosome. Assuming that meiosis in males is ‘always normal', what is the expected frequency of XXX females and XO males arising from any number of fertilized eggs? Do not be concerned as to whether it is lethal or not.arrow_forwardTable 8.1 shows that Turner syndrome occurs when an individual inherits one X chromosome but lacks a second sex chromosome. Can Turner syndrome be due to nondisjunction during oogenesis, spermatogenesis, or both? If a phenotypically normal couple has a color-blind child (due to a recessive X-linked allele) with Turner syndrome, did nondisjunction occur duringoogenesis or spermatogenesis in this child’s parents? Explain your answer.arrow_forwardShow via a diagram how the product(s) of a meiotic (either I or II) nondisjunction involving the X chromosome of a human female could, when fertilized by a normal male gamete, result in an offspring with Kleinfelter’s syndrome.arrow_forward
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