Bundle: Biology: The Unity and Diversity of Life, 14th + LMS Integrated for MindTap Biology, 1 term (6 months) Printed Access Card
14th Edition
ISBN: 9781305774384
Author: Cecie Starr, Ralph Taggart, Christine Evers, Lisa Starr
Publisher: Cengage Learning
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Chapter 10, Problem 3CT
Almost all calico cats (one is pictured in FIGURE 10.7B) are female. Why?
B When this calico cat was an embryo, one of the two X chromosomes was inactivated in each of her cells. The descendants of the cells formed her adult body, which is a mosaic for expression of X chromosome genes. Black fur arises in patches where genes on the X chromosome inherited from one parent are expressed; orange fur arises in patches where genes on the X chromosome inherited from the other parent are expressed.
FIGURE 10.7 ►Animated X chromosome inactivation.
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Figure 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.
In humans, dosage compensation is accomplished by:
inactivating one X chromosome in female somatic cells
inactivating one homolog from each homologous pair of chromosomes in female somatic cells
inactivating the Y chromosome in male somatic cells
increasing gene expression from the X chromosome in male somatic cell
Human females who are heterozygous for an X-linked recessive allele sometimes exhibit mild expression of the trait. However, such mild expression of X-linked traits in females who are heterozygous for Xlinked alleles is not seen in Drosophila. What might cause this difference in the expression of X-linked genes between human females and female Drosophila? (Hint: In Drosophila, dosage compensation is accomplished by doubling the activity of genes on the X chromosome of males.)
Chapter 10 Solutions
Bundle: Biology: The Unity and Diversity of Life, 14th + LMS Integrated for MindTap Biology, 1 term (6 months) Printed Access Card
Ch. 10 - The expression of a gene may depend on _______. a....Ch. 10 - Prob. 2SQCh. 10 - Binding of ______ to _______ in DNA can increase...Ch. 10 - Prob. 4SQCh. 10 - Prob. 5SQCh. 10 - Muscle cells differ from bone cells because...Ch. 10 - Prob. 7SQCh. 10 - Homeotic gene products _______. a. flank a...Ch. 10 - A gene that is knocked out is ________. a. deleted...Ch. 10 - Which of the following includes all of the others?...
Ch. 10 - Prob. 11SQCh. 10 - Effect of Paternal Grandmothers Food Supply on...Ch. 10 - Prob. 2DAACh. 10 - Effect of Paternal Grandmothers Food Supply on...Ch. 10 - Prob. 12SQCh. 10 - A cell with a Barr body is ___ . a. a bacterium b....Ch. 10 - Operons _____. a. only occur in bacteria b. have...Ch. 10 - Prob. 15SQCh. 10 - Why are some genes expressed and some not?Ch. 10 - Prob. 2CTCh. 10 - Almost all calico cats (one is pictured in FIGURE...Ch. 10 - The photos above show flowers from Arabidopsis...
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