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 21PDQ
In mice, the Sry gene (see Section 7.2) is located on the Y chromosome very close to one of the pseudoautosomal regions that pairs with the X chromosome during male meiosis. Given this information, propose a model to explain the generation of unusual males who have two X chromosomes (with an Sry-containing piece of the Y chromosome attached to one X chromosome).
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In mice, the Sry gene is located on the Y chromosome very close to one of the pseudoautosomal regions that pairs with the X chromosome during male meiosis. Given this information, propose a model to explain the generation of unusual males who have two X chromosomes (with an Sry-containing piece of the Y chromosome attached to one X chromosome).
Meiosis is characterized by the pairing of homologouschromosomes during prophase I. In many species, an elaboratestructure called the synaptonemal complex forms betweenhomologues. During this pairing, homologues may exchangechromosomal material at sites called chiasmata. In meiosis I, thehomologues separate from each other, reducing the chromosomenumber to the haploid state (thus the reductive division). It isfollowed by a second division without replication, during whichsister chromatids become separated. The result of meiosis I and IIis four haploid cells.
If sister chromatids separated at the first division, would meiosis still work?
Mutations in genes that affect meiosis have been identified in many different model organisms. Most of these mutations result in aneuploidy of more than a single chromosome and are nearly sterile. Explain why this is the case.
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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- 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. Question is also in the picture.arrow_forwardConsider a cell with 2 pairs of homologous chromosomes where Chromosome 1 with genes VWXYZ is the homolog of Chromosome 2 with genes vwxyz while Chromosome 3 with genes PQRST is the homolog of Chromosome 4 with genes parst. If a reciprocal translocation occurred between Chromosome 1 YZ genes and Chromosome 3 ST genes, give the following gamete types produced after meiosis: (Answer in Arabic numbers only) 1. Gamete/s with non-recombinant chromosomes 2. Gamete/s with 1 recombinant chromosome 3. Gamete/s with 2 recombinant chromosomes 4. Gamete/s with gene duplications 5. Gamete/s with gene deletions 6. Gamete/s with 2 normal chromosome sequences 7. Gamete/s with 1 normal chromosome sequence 8. Gamete/s with balanced translocation 9. Gametes/ with all dominant genes 10. Gamete/s with all recessive genes 11. Gamete/s with 10 different genes 12. Gamete/s with TSXWV genes 13. Gamete/s with vwxyz genes 14. Gamete/s with pqrst genes 15.Gamete/s with PORYZarrow_forwardThough an individual with abberations such as Robertsonian translocation may be phenotypically normal, they can generate gametes through meiosis that have atypical organizations of chromosomes, resulting in recurrent fetal abnormalities or miscarriages. Why, despite these Robertsonian translocations, are affected cells still able to generate typical gametes through meiosis?arrow_forward
- In fruit flies, chromosomal crossing over does not occur in meiosis in males, whereas crossing over does occur in meiosis in females. In fruit flies that are heterozygous at many genes (i.e. many maternal and paternal versions of the genes differ), at what stage would cells no longer be heterozygous for any gene during the process of meiosis? a)After the second meiotic division in males, and after the first meiotic division in females. b)After the second meiotic division in both males and females. c)After the first meiotic division in both males and females. d)After the first meiotic division in males, and after the second meiotic division in females.arrow_forwardSketch a series of diagrams showing each of the following, making sure to end each series with haploid cells:(a) How a pair of alleles for a single locus segregate in meiosis(b) How the alleles of two unlinked loci assort independently in meiosis(c) How the alleles of two linked loci undergo genetic recombinationarrow_forwardA male Drosophila melanogaster has the genotype A/a; B/b; C/c; XD/Y (all genes are on separate chromosomes). How many different sperm genotypes can it produce through meiosis of one single pre-gametic (2n) cell? (remember, there is no crossing over in male Drosophila) Explain.arrow_forward
- In Drosophila, the X chromosomes may become attached to one another (XXn ) such that they always segregate together. Some flies thus contain a set of attached X chromosomes plus a Y chromosome. (a) What sex would such a fly be? Explain why this is so. (b) Given the answer to part (a), predict the sex of the off-spring that would occur in a cross between this fly and a normal one of the opposite sex. (c) If the offspring described in part (b) are allowed to interbreed, what will be the outcome?arrow_forwardFemale 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?arrow_forwardWhat would be the consequences to the outcome of meiosis if SPO11 is absent? Explain your reason.arrow_forward
- One reason that worker bees forgo their own reproduction to help their sister (the queen) reproduce is that female bees are more closely related to their sisters than they are to their own offspring. This quirk of genetics results from the fact that bees have haplodiploid sex determination, in which females are diploid, with a mother and a father, but males are haploid, developing from unfertilized eggs. Because males are haploid, they produce sperm by mitosis. Explainwhy haplodiploid sex determination causes females to be more closely related to their sisters than to their offspring.arrow_forwardWe have discussed meiosis in yeast. One ascus e one melotic event. Two haploid yeast strains are crossed together, one wild type, the other mutant for 2 linked genes. The resulting diploid strain undergoes melosis eventually (=many meiotic events > many asci). A. What will the results be if the 2 genes are very far away from each other (certainly more than 50 map units)? B. What will the results be if the two genes are right next to each other, "no distance at all, zero distance"? (Explain your answers). Results here are patterns of asci and their percentages. Like for example "50% tetratypes, 0% ditypes", etc. If you forgot what a ditype or a tetratype is, you can illustrate them like that.arrow_forwardKuliev and Verlinsky (2004) state that there was a relatively high number of separation errors at meiosis I. In these cases the centromere underwent a premature division, occurring at meiosis I rather than meiosis II. Regarding chromosome 21, what would you expect to be the chromosome 21 complement in the secondary oocyte in which you saw a single chromatid (monad) for chromosome 21 in the first polar body? If this secondary oocyte was involved in fertilization, what would be the expected consequences?arrow_forward
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