Study Guide for Campbell Biology
11th Edition
ISBN: 9780134443775
Author: Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Jane B. Reece, Martha R. Taylor, Michael A. Pollock
Publisher: PEARSON
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Chapter 15, Problem 17TYK
Some girls who fail to undergo puberty are found to have Swyer syndrome, a condition in which they are externally female but have an XY genotype. Which of the following statements may explain the origin of this syndrome?
- a. A mutation in the XIST gene, which codes for RNA molecules that coat the X chromosome and initiate X-inactivation, must have occurred.
- b. A nondisjunction in the egg from the mother resulted in both sex chromosomes coming from the father. Genomic imprinting of the father’s X chromosome then caused the development of a female
phenotype . - c. These individuals are actually XXY; the second X is not seen because it is condensed into a Barr body. They have small testes and are sterile but otherwise appear female.
- d. A mutation or deletion of the SRY gene on the Y chromosome prevented development of testes and production of the male sex hormones required for a male phenotype.
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Chapter 15 Solutions
Study Guide for Campbell Biology
Ch. 15 - Complete the following summary of Morgans crosses...Ch. 15 - Two normal color-sighted individuals have two...Ch. 15 - In a testcross between a heterozygote tall,...Ch. 15 - With unlinked genes, an equal number of parental...Ch. 15 - The following recombination frequencies have been...Ch. 15 - a. What is the difference between an organism with...Ch. 15 - Prob. 7IQCh. 15 - Prob. 8IQCh. 15 - Mendels law of independent assortment applies to...Ch. 15 - You have found a new mutant phenotype in fruit...
Ch. 15 - Prob. 3SYKCh. 15 - Prob. 4SYKCh. 15 - Thomas Hunt Morgan firmly established the location...Ch. 15 - Prob. 2TYKCh. 15 - Sex-linked traits a. are coded for by genes...Ch. 15 - Prob. 4TYKCh. 15 - Prob. 5TYKCh. 15 - Prob. 6TYKCh. 15 - Prob. 7TYKCh. 15 - Prob. 8TYKCh. 15 - Prob. 9TYKCh. 15 - Prob. 10TYKCh. 15 - Consider three genes on the X chromosome: A, B,...Ch. 15 - Prob. 12TYKCh. 15 - Genomic imprinting a. explains cases in which the...Ch. 15 - Prob. 14TYKCh. 15 - Prob. 15TYKCh. 15 - Suppose that alleles for an X-linked character for...Ch. 15 - Some girls who fail to undergo puberty are found...Ch. 15 - Prob. 18TYKCh. 15 - The genetic event that results in Turner syndrome...Ch. 15 - Prob. 20TYKCh. 15 - Prob. 1GPCh. 15 - Prob. 2GPCh. 15 - Prob. 3GPCh. 15 - Prob. 4GPCh. 15 - Prob. 5GPCh. 15 - Red-green color blindness is caused by a...
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- 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 ?arrow_forwardInfants born with Patau syndrome have an extra copy of chromosome 13, which leads to developmental abnormalities such as cleft lip and palate, small eyes, and extra fingers and toes. Another type of genetic disorder, Turner syndrome, results from the presence of only one sex chromosome—an X chromosome. Individuals born with one X chromosome are females exhibiting few noticeable defects until puberty, when they fail to develop normal breasts and internal sexual organs. what is more information about these genetic diseases on how they relate and differ?arrow_forwardInfants born with Patau syndrome have an extra copy of chromosome 13, which leads to developmental abnormalities such as cleft lip and palate, small eyes, and extra fingers and toes. Another type of genetic disorder, Turner syndrome, results from the presence of only one sex chromosome—an X chromosome. Individuals born with one X chromosome are females exhibiting few noticeable defects until puberty, when they fail to develop normal breasts and internal sexual organs. what is more information about these genetic diseases on how they relate and differ? What are the meiotic events that could lead to the birth of an individual with either Patau syndrome or Turner syndrome as shown above?arrow_forward
- Following X-chromosome inactivation, most of the genes on theinactivated X chromosome are silenced. Explain how. Name onegene that is not silenced.arrow_forward4) Explain why you can NOT typically have a Male Calico cat. 5) Can you think of any unusual situation where you might be able to have a Male Calico cat? Explain how this might occur 6) Explain how X chromosome inactivation takes place in mammals at the chromosomal and molecular level. B. What genes are involved in inactivating a human X chromosome? C. What role does X chromosome-specific inactivating transcript --XIST-- non coding RNA play in the inactivation of the human X chromosome.arrow_forwardOccasionally, a mouse X chromosome is broken into two pieces and each piece becomes attached to a different autosome. A scientist studies this cell, and finds that the genes on only one of the two pieces undergo inactivation. By referring to the mechanism of X-chromosome inactivation, explain the observation made by the scientist.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_forwardA cytogeneticist is studying the cells from an abnormal female monkey. In some cells, she finds that both X-chromosomes are active (i.e. not packaged into a Barr body), although one of the X-chromosomes appears shorter. She also finds that one of the autosomes are packaged as a Barr body, and she suspects that a translocation event might have been involved. By referring to the mechanism of X-chromosome inactivation, explain the observations made by the scientistarrow_forwardFigure 19.25 shows that the Sxl protein binds to the mRNA of the msl-2 gene, inhibiting translation of the mRNA’s proper reading frame. The MSL-2 protein is a transcription factor that binds to the X chromosome in XY males to double the level of X-linked gene transcription, thus equalizing X-linked gene expression in XY males and XX females. a. In which sex, XY males or XX females, would the Sxl protein bind to the msl-2 mRNA? b. As discussed in Problem 35, some Sxl alleles are lethal to females and others are lethal to males. Is the function of Sxl in regulating the synthesis of Msl-2 protein sufficient to explain the sex-specific lethality caused by both kinds of alleles? c. Predict the effect of loss-of-function mutations in msl-2 on male and female fertility and viability.arrow_forward
- Imagine a scenario in which prenatal testing of a human female fetus indicates that the baby will have a normal XX karyotype but is heterozygous for a mutation that inactivates the Xist promoter. Allele “Xr” represents the mutated version of the Xist promoter, and “XR” represents the normal version of the Xist promoter. How will this mutation affect the process of X inactivation?A. "X inactivation will still be random with both mutant and normal X chromosomes being randomly inactivated" B. "The chromosome with the mutant Xist promoter will always be active" C. "The chromosome with the mutant Xist promoter will always be inactivated" D. "The normal X chromosome (no mutation in Xist) will always be active" E. "The normal X chromosome (no mutation in Xist) will always be inactivated"arrow_forwardAlthough most tortoiseshell cats are female, a litter of kittens will occasionally contain a male tortoiseshell. Which of the following can explain tortoiseshell coat color in a male kitten? Please explain in detail. The male kitten has an extra Y chromosome The male kitten has an extra X chromosome The male kitten has no X chromosome The male kitten cannot carry out X-inactivationarrow_forwardThe gene causing Coffin-Lowry syndrome (OMIM 303600) was recently identified and mapped on the human X chromosome. Coffin-Lowry syndrome is a rare disorder affecting brain morphology and development. It also produces skeletal and growth abnormalities, as well as abnormalities of motor control. Coffin-Lowry syndrome affects males who inherit a mutation of the X-linked gene. Most carrier females show no symptoms of the disease but a few carriers do. These carrier females are always less severely affected than males. Offer an explanation for this finding.arrow_forward
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