Genetics: From Genes to Genomes
6th Edition
ISBN: 9781259700903
Author: Leland Hartwell Dr., Michael L. Goldberg Professor Dr., Janice Fischer, Leroy Hood Dr.
Publisher: McGraw-Hill Education
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Chapter 19, Problem 13P
A C. elegans (nematode) gene called par-1 helps to determine the AP axis of the animal early in development. Scientists determined that par-1 is pleiotropic—it also has a later function in forming the vulva of the adult animal. How could researchers circumvent the lethality of par-1 mutants to observe the later function of the par-1 gene? (Hint: C. elegans larvae can eat bacteria expressing RNAi for any gene.)
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Another way to study the role of proteins (e.g., transcription factors) that function in development is to microinject the mRNA that encodes a protein, or the purified protein itself, into an oocyte or embryo, and then determine how this affects the subsequent development of the embryo, larva, and adult. For example, if Bicoid protein is injected into the posterior region of an oocyte, the resulting embryo will develop into a larva that has anterior structures at both ends. Based on your understanding of the function of each developmental gene, what would be the predicted phenotype if the following proteins or mRNAs were injected into normal oocytes?
A. Nanos mRNA injected into the anterior end of an oocyte
B. Antp protein injected into the posterior end of an embryo
C. Toll mRNA injected into the dorsal side of an early embryo
The eyes of Drosophila develop from imaginal discs, groups of cells set aside in the fly embryo that differentiate into the adult structures during the pupal stage. Despite their importance in nature, eyes are dispensable for fruitfly life in the laboratory. Devise a genetic screen to identify genes directing development of the fly eye. What complications might arise from genetic screens targeting an organ that differentiates late in development?
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a)Using this knowledge how would screen for Drosophila mutants that have an impaired circadian rhythm?
b)In each case, how would you clone the genes you identified by mutation?
Chapter 19 Solutions
Genetics: From Genes to Genomes
Ch. 19 - Match each of the terms in the left column to the...Ch. 19 - a. If you were interested in the role of a...Ch. 19 - Early C. elegans embryos display mosaic...Ch. 19 - Hypomorphic mutations in the wingless gene of...Ch. 19 - Prob. 5PCh. 19 - In 1932, H. J. Muller suggested a genetic test to...Ch. 19 - a. Explain how you could use worms transformed...Ch. 19 - Suppose you want to determine whether a particular...Ch. 19 - Sevenless is an unusual receptor protein in that...Ch. 19 - Suppose that you generated flies containing a...
Ch. 19 - Drosophila researchers have collected many strains...Ch. 19 - As an alternative to random mutagenesis,...Ch. 19 - A C. elegans nematode gene called par-1 helps to...Ch. 19 - The molecular identity of the fruit fly rugose...Ch. 19 - To determine the focus of action of boss,...Ch. 19 - Suppose a particular gene is required for early...Ch. 19 - Researchers have exploited Minute mutations in...Ch. 19 - Some ts alleles are temperature sensitive during...Ch. 19 - The following figure shows the temperature-shift...Ch. 19 - A temperature-sensitive allele of the gene...Ch. 19 - Hypomorphic alleles of a pleiotropic gene...Ch. 19 - In addition to the maternal effect genes that...Ch. 19 - The yan gene encodes a transcription factor that...Ch. 19 - Recall from Chapter 17 that in Drosophila, sex...Ch. 19 - a. Explain the difference between maternal...Ch. 19 - In the 1920s, Arthur Boycott, working with the...Ch. 19 - The Drosophila mutant screen shown on the...Ch. 19 - Some genes are required both zygotically and...Ch. 19 - How would a human with a mutation in a maternal...Ch. 19 - One important demonstration that Bicoid is an...Ch. 19 - The hunchback gene contains a 5 transcriptional...Ch. 19 - In flies developing from eggs laid by a...Ch. 19 - Wild-type embryos and mutant embryos lacking the...Ch. 19 - The Drosophila even-skipped eve gene has four...Ch. 19 - In Drosophila with loss-of-function mutations...Ch. 19 - It is crucial to the development of Drosophila...Ch. 19 - In the plant Arabidopsis thaliana, every flower is...
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- In flies, the gap gene kruppel is expressed in a broad band in the middle of the embryo with giant expressed as its anterior border and knirps at its posterior border. How is the expression of kruppel limited to this band in the embryo? Describe the spatial regulation of the kruppel gene.arrow_forwardUsing a transgenic technique, propose an experiment to determine whether Cdx2 is sufficient for trophoblast development in the mouse embryo. Describe two results that you would expect to observe at the blastocyst stage if Cdx2 is indeed sufficient for trophoblast development. Be as specific as possible regarding the transgene that you propose for this experiment (including what gene's enhancer you would use in the transgene). Note: you do not need to explain the details of how a transgenic mouse is made. Describe the experiment in steps (Step 1: ..., Step 2: ... etc) and please keep your answer to under 150 words. tips: DONT talk about stop cassetes/memory cassetes, focus on transgenes Paper called "Cdx2 is required for correct cell fate specification and differentiation of trophectoderm in the mouse blastocyst" gave lots of results that you might see,, 6 diff ways that cdx2 is required for trophoblasts need specific gene enhancer (dont just say "expressed enhancer in genital…arrow_forwardThe MyoD gene in mammals plays a role in skeletal muscle-cell differentiation, whereas the Hox genes are homeotic genes that play a role in the differentiation of particular regions of the body. Explain how the functions of these genes are similar and different.arrow_forward
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- Suppose you want to determine whether a particulargene X is important for specification of the pharynx,but mutations in this same gene disrupt embryonicdevelopment well before pharyngeal structures appear.How could you use myo-2::GFP, the myo-2 promoter,the DNA sequence of gene X, and your knowledge ofRNA interference (RNAi) to generate worms that lackgene X expression in the pharynx but express gene Xin all other tissues in which it is expressed in wildtype C. elegans?arrow_forwardOur understanding of maternal effect genes has been greatly aided by their identification in experimental organisms such as Drosophila melanogaster and Caenorhabditis elegans. In experimental organisms with a short generation time, geneticists have successfully searched for mutant alleles that prevent the normal process of embryonic development. In many cases, the offspring die at early embryonic or larval stages. These are called maternal effect lethal alleles. How would a researcher identify a mutation that produced a recessive maternal effect lethal allele?arrow_forwardWhat would be the most likely result of injecting bicoid mRNA into the posterior end of a Drosophila embryo and inhibiting the translation of nanos mRNA?arrow_forward
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