In Drosophila, the wild-type red eye color is produced by the X-linked allele
If a male Drosophilahas white eye color as a result of inactivation of
Several male progeny of a female carrier of the mutantallele have red sectors on their eyes. The number andsize of the sectors vary among the males. Explain theorigin of these red sectors, and account for the variationin number and size.
If Southern blotting is used to compare DNA isolatedfrom a white sector and a red sector of the same eye, is a difference in DNA fragment size expected? Explain.
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Genetic Analysis: An Integrated Approach (2nd Edition)
- In an in situ hybridization experiment, a certain clonebound to only the X chromosome in a boy with no diseasesymptoms. However, in a boy with Duchenne musculardystrophy (X-linked recessive disease), it bound to theX chromosome and to an autosome. Explain. Could thisclone be useful in isolating the gene for Duchenne muscular dystrophy?arrow_forwardIn the Fast Forward Box Visualizing X Chromosome Inactivation in Transgenic Mice, suppose the investigators had looked at the expression of green and red fluorescent protein in early mouse embryos, when the embryos have fewer than 500 cells. What patterns would they likely have observed?arrow_forwardIn Drosophila, a female fly is heterozygous for three mutations, Bareyes (B), miniature wings (m), and ebony body (e). Note that Bar isa dominant mutation. The fly is crossed to a male with normal eyes,miniature wings, and ebony body. The results of the cross are asfollows.111 miniature29 wild type117 Bar26 Bar, mimatue101 Bar, ebony31 Bar, miniature, ebony35 ebony115 miniature, ebonyInterpret the results of this cross. If you conclude that linkage isinvolved between any of the genes, determine that map distance(sbetween them.arrow_forward
- Knock out mice that are mutant for a gene product X die. Variants of the X gene that were reintroduced through homologous recombination indicate that variant proteins that lack the C-terminal region of the protein cannot rescue the lethality (did not allow them to live), and always localized to the cytoplasm. Those that retained the C-terminal region rescued the lethality (conferred viability!) and were consistently localized within the nucleus. RNA-seq analysis of the mutant cells vs the wild-type cells indicated that the expression of many genes that are essential for neural function was reduced in the knock-out mutant cells. The N-terminal region of Protein X is 100% conserved between mouse and humans at both the amino acid and the nucleotide level. The predicted mouse mRNA sequence is shown below where the AUG corresponds to the translational start site (AUG). 5’-AUGUUUACAGAGGGGAAU... -3’ d) What motif could be present to direct this protein to its correct destination? e)…arrow_forwardKnock out mice that are mutant for a gene product X die. Variants of the X gene that were reintroduced through homologous recombination indicate that variant proteins that lack the C-terminal region of the protein cannot rescue the lethality (did not allow them to live), and always localized to the cytoplasm. Those that retained the C-terminal region rescued the lethality (conferred viability!) and were consistently localized within the nucleus. RNA-seq analysis of the mutant cells vs the wild-type cells indicated that the expression of many genes that are essential for neural function was reduced in the knock-out mutant cells. The N-terminal region of Protein X is 100% conserved between mouse and humans at both the amino acid and the nucleotide level. The predicted mouse mRNA sequence is shown below where the AUG corresponds to the translational start site (AUG). 5’-AUGUUUACAGAGGGGAAU... -3’ Q3a) Using a total RNA sample obtained from human cells, what is the first primer you would…arrow_forwardTo detect the CAG repeat expansion with a particular gene where 30 repeats in Normal changes to 250 repeats in a certain disease, how can we diagnose the condition. How To identify Y chromosome microdeletion ( which involves the deletion of AZF locus) using conventional karyotyping? If not then why. How will you diagnose a chromosomal translocation event?arrow_forward
- Gene X is expressed in the developing brain, heart, andlungs of mice. Mutations that selectively affect gene Xfunction in these three tissues map to three differentregions (A, B, and C, respectively) 5′ of the X codingregion.a. Explain the nature of these mutations.b. Draw a map of the X locus consistent with the preceding information.c. How would you test the function of the A, B, and Cregions?arrow_forwardThe completely synthetic yeast chromosome Syn IIIcontains a loxP site in the 3′ UTR of every gene thatis potentially nonessential to yeast survival. As youwill recall from Chapter 6, loxP sites are targets ofsite-specific recombination. The researchers who constructed Syn III included these loxP sites as a way to“scramble” the chromosome, meaning that parts ofthe chromosome could easily be deleted or rearranged.The goal of these investigations is to drive the evolution of Syn III so as to define a minimal genome thatcan support the life of this organism. Outline the experiment the researchers would do to scramble Syn IIIin order to define a minimal genome.arrow_forwardThe gene controlling ABO blood type and the gene underlying nail-patella syndrome are said to show linkage. What does that mean in terms of their relative locations in the genome? What does it mean in terms of how the two traits are inherited with respect to each other?arrow_forward
- A yeast geneticist irradiates haploid cells of a strain thatis an adenine-requiring auxotrophic mutant, caused bymutation of the gene ade1. Millions of the irradiatedcells are plated on minimal medium, and a small number of cells divide and produce prototrophic colonies.These colonies are crossed individually with a wildtype strain. Two types of results are obtained:(1) prototroph × wild type : progeny all prototrophic(2) prototroph × wild type : progeny 75% prototrophic,25% adenine-requiring auxotrophsa. Explain the difference between these two types ofresults.b. Write the genotypes of the prototrophs in each case.c. What progeny phenotypes and ratios do you predictfrom crossing a prototroph of type 2 by the original ade1auxotroph?arrow_forwardExplain why loss-of-function hedgehog and smoothened mutations yield the same phenotype in flies, but a loss-of- function patched mutation yields the opposite phenotype.arrow_forwardFlies homozygous for recessive null mutations in thesevenless (sev) or bride-of-sevenless (boss) genes have the same mutant phenotype: Every ommatidium(facet) in their eyes lacks photoreceptor cell 7 (R7).The R7 cells enable flies to detect UV light.a. Given that flies normally move toward light, suggest a screening method that would enable you toidentify mutations in additional genes required forR7 determination.b. Would you be able to recover mutations in everygene required for R7 development with yourmethod? Explain.c. How could you tell whether any of the new mutationsyou found in your screen are alleles of sev or boss?d. Suppose you found one recessive mutant allele ofa gene not previously known to be involved in eyedevelopment. How could you use this allele in anew mutagenesis screen to find additional allelesof this gene? Why might you want additional mutant alleles to study the process?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning