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 22P
In addition to the maternal effect genes that establish anterior/posterior polarity in the Drosophila embryo (like bicoid and nanos), other maternal effect genes, including dorsal, pelle, and Toll, independently determine dorsal/ventral polarity. The dorsal gene encodes a transcription factor (Dorsal), originally deposited in the egg cytoplasm, that determines ventralness in a concentration-dependent manner. As shown in the following figure(Wild type), a gradient of Dorsal nuclear localization exists in early embryos: Cells whose nuclei have the highest Dorsal protein concentration become the ventral-most cells, cells whose nuclei have no Dorsal protein aredorsal-most, and lateral cells “learn” their positions and fates through the particular intermediate Dorsal proteinlevels in their nuclei. The figure shows sections through blastoderm embryos, where D = dorsal and V = ventral
Embryos from mothers homozygous for dorsal null mutations are dorsalized-every cell along the dorsal/ventral axis “thinks” it is the ventral-most cell. Embryos from mothers homozygous for loss-of-function pelle mutations or heterozygous for gain-of-function (constitutively active) TollD> mutations show altered patterns of Dorsal protein localization, as shown in the figure. Pelle and Toll expression are unaltered in dorsal loss-of-function mutants (not shown).
| a. | Describe the alterations in Dorsal protein localization in embryos produced by pelle-/pelle- or TollD/Toll+mutant mothers. |
| b | Based on the information given, order the dorsal, pelle, and Toll genes in a pathway. |
| c. | The two kinds of embryos described in part (a) die just before hatching. Describe their morphological mutant |
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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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