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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Textbook Question
Chapter 19, Problem 35P
In Drosophila with loss-of-function mutations affecting the Ubx gene, transformations of body segments are always in the anterior direction. That is, in bx mutants, the anterior compartment of T3 is transformed into the anterior compartment of T2, whereas in pbx mutants, the posterior compartment of T3 is transformed into the posterior compartment of T2 (Fig. 19.26). In wild type, the Ubx gene itself is expressed in posterior T2–anterior A7 (PS5–PS12) and most strongly in posterior T3–anterior A1 (PS6). (See Fig. 19.29.)
a. | The Abd-B gene is transcribed in the abdominal parasegments 10–13. Assuming the mode of function of Abd-B is the same as that of Ubx, what is the likely consequence of homozygosity for a null allele of Abd-B (that is, what segmental or parasegmental transformations would you expect to see)? |
b. | Because Abd-A is expressed in parasegments 7–12, all three genes of the BX-C (Ubx, Abd-A, and Abd-B) are transcribed in parasegments 10–12 (see Fig. 19.29). Why then are the abdominal parasegments 10, 11, and 12 morphologically distinguishable? |
c. | What parasegment transformations would you expect to see in an animal deleted for all three genes of the BX-C (Ubx, Abd-A, and Abd-B)? |
d. | Certain Contrabithorax mutations in the BX-C cause transformations of wing to haltere. Propose an explanation for this you anticipate that Contrabithorax mutations would be dominant or recessive to wild type? Explain. |
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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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