Genetics: From Genes to Genomes
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 19P

The following figure shows the temperature-shift analysis of C. elegans embryos from mothers homozygous for a temperature-sensitive allele of the zyg-9 gene, which helps determine the polarity of the early embryo. Each dot represents an individual embryo subjected to a short (5-minute) pulse of high temperature. Green dots indicate that the embryo ultimately survives and becomes a normal worm, whereas red dots represent animals with abnormal polarity that ultimately die.

 Chapter 19, Problem 19P, The following figure shows the temperature-shift analysis of C. elegans embryos from mothers

a. At what time after fertilization is the zyg-9 gene required for normal development of C. elegans?
b. The same results were obtained whether the sperm used in the fertilization had wild-type or mutant alleles of zyg-9. What does this fact say about the source of the Zyg-9 protein that is present during the narrow window of time when it is required?
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In the nematode C. elegans, homozygosity for the e mutant allele causes an extreme "uncoordinated" phenotype, where the worm completely loses its ability to move. Examination of 100 individuals with genotype e/e reveals that 60 mutant worm can't move at all, 35 show a very reduced ability to move, and the remaining 5 seem to have a completely wild-type phenotype with respect to movement ability. These observations suggest that e has O incomplete penetrance and variable expressivity O low expressivity and variable penetrance Ohigh expressivity and variable penetrance O high penetrance and incomplete expressivity
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Chapter 19 Solutions

Genetics: From Genes to Genomes

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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