The top chromosome carries the recessive b allele, and the bottom chromosome carries the dominant B allele. Gene region ъ 5' 3' 3" 5' в A double-strand break occurs within the recessive gene. в A region adjacent to the double- strand break is digested away, which eliminates the recessive b allele. в Strand invasion causes D-loop formation. в Gap repair synthesis uses the strands from the dominant B allele to fill in the region. в The intertwined strands are resolved. в в Both chromosomes carry the B allele. FIGURE 20.5 Gene conversion by gap repair synthesis accord- ing to the double-strand break model. A gene is found in two alleles, des- ignated b and B. A double-strand break occurs in the DNA encoding the b alkele. Both of these DNA strands are digested away, thereby eliminating the b allele. A complementary DNA strand encoding the B allele migrates to this region and provides the template to synthesize a new double-stranded region. Following resolution, both DNA double helices carry the B allele.

The top chromosome carries the recessive b allele, and the bottom chromosome carries the dominant B allele. Gene region ъ 5' 3' 3" 5' в A double-strand break occurs within the recessive gene. в A region adjacent to the double- strand break is digested away, which eliminates the recessive b allele. в Strand invasion causes D-loop formation. в Gap repair synthesis uses the strands from the dominant B allele to fill in the region. в The intertwined strands are resolved. в в Both chromosomes carry the B allele. FIGURE 20.5 Gene conversion by gap repair synthesis accord- ing to the double-strand break model. A gene is found in two alleles, des- ignated b and B. A double-strand break occurs in the DNA encoding the b alkele. Both of these DNA strands are digested away, thereby eliminating the b allele. A complementary DNA strand encoding the B allele migrates to this region and provides the template to synthesize a new double-stranded region. Following resolution, both DNA double helices carry the B allele.

Biology: The Unity and Diversity of Life (MindTap Course List)

15th Edition

ISBN:9781337408332

Author:Cecie Starr, Ralph Taggart, Christine Evers, Lisa Starr

Publisher:Cecie Starr, Ralph Taggart, Christine Evers, Lisa Starr

Chapter14: Chromosomes And Human Inheritance

Section: Chapter Questions

Problem 6SQ: Choose the statement that is incorrect. a. A son can inherit a recessive allele on an X chromosome...

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The XG locus on the human X chromosome has twoalleles, XG+ and XG. The XG+ allele causes the presence of the Xg surface antigen on red blood cells,while the recessive XG allele does not allow antigento appear. The XG locus is 10 m.u. from the STSlocus. The STS+ allele produces normal activity ofthe enzyme steroid sulfatase, while the recessive STSallele results in the lack of steroid sulfatase activityand the disease ichthyosis (scaly skin). A man withichthyosis and no Xg antigen has a normal daughterwith Xg antigen. This daughter is expecting a child.a. If the child is a son, what is the probability he willlack Xg antigen and have ichthyosis?b. What is the probability that a son would have boththe antigen and ichthyosis?c. If the child is a son with ichthyosis, what is theprobability he will have Xg antigen?
The maternal-effect mutation bicoid (bcd) is recessive. Inthe absence of the bicoid protein product, embryogenesis isnot completed. Consider a cross between a female heterozygousfor the bicoid mutation (bcd+/ bcd-) and a homozygousmale(bcd-/ bcd-). Predict the outcome (normal vs. failed embryogenesis) inthe F1 and F2 generations of the cross described.
. A diploid strain of yeast was made by mating a haploidstrain with a genotype w−, x−, y−, and z− with a haploidstrain of opposite mating type that is wild type for thesefour genes. The diploid strain was phenotypically wildtype. Four different X-ray-induced diploid mutantswith the following phenotypes were produced fromthis diploid yeast strain. Assume a single new mutation is present in each strain.Strain 1 w− x+ y− z+Strain 2 w+ x− y− z−Strain 3 w− x+ y− z−Strain 4 w− x+ y+ z+When these mutant diploid strains of yeast go throughmeiosis, each ascus is found to contain only two viablehaploid spores.a. What kind of mutations were induced by X-rays tomake the listed diploid strains?b. Why did two spores in each ascus die?c. Are any of the genes w, x, y, or z located on thesame chromosome?d. Give the order of the genes that are found on thesame chromosome
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Which letter is pointing at the centromere region? В A C
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The maternal-effect mutation bicoid (bcd) is recessive. Inthe absence of the bicoid protein product, embryogenesis isnot completed. Consider a cross between a female heterozygousfor the bicoid mutation (bcd+/ bcd-) and a homozygousmale(bcd-/ bcd-). How is it possible for a male homozygous for the mutationto exist?
In 1-3 sentences define Sense, Missense, Nonsense mutations, Frameshift mutations, Allelic expansion, trinucleotide repeat